Forbes:

I started Docstoc in my 20’s, made the cover of one of those cliché “20 Under 20” lists, and today I employ an amazing group of 20-somethings. Call me a curmudgeon, but at 34, how I came up seems so different from what this millennial generation expects. I made a lot of mistakes along the way, and I see this generation making their own. In response, here are my 20 Things 20-Year-Olds Don’t Get.

Time is Not a Limitless Commodity – I so rarely find young professionals that have a heightened sense of urgency to get to the next level. In our 20s we think we have all the time in the world to A) figure it out and B) get what we want. Time is the only treasure we start off with in abundance, and can never get back. Make the most of the opportunities you have today, because there will be a time when you have no more of it.

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You’re Talented, But Talent is Overrated - Congratulations, you may be the most capable, creative, knowledgeable & multi-tasking generation yet. As my father says, “I’ll Give You a Sh-t Medal.” Unrefined raw materials (no matter how valuable) are simply wasted potential. There’s no prize for talent, just results. Even the most seemingly gifted folks methodically and painfully worked their way to success. (Tip: read “Talent is Overrated”)

We’re More Productive in the Morning – During my first 2 years at Docstoc (while I was still in my 20’s) I prided myself on staying at the office until 3am on a regular basis. I thought I got so much work done in those hours long after everyone else was gone. But in retrospect I got more menial, task-based items done, not the more complicated strategic planning, phone calls or meetings that needed to happen during business hours. Now I stress an office-wide early start time because I know, for the most part, we’re more productive as a team in those early hours of the day.

Social Media is Not a Career – These job titles won’t exist in 5 years. Social media is simply a function of marketing; it helps support branding, ROI or both. Social media is a means to get more awareness, more users or more revenue. It’s not an end in itself. I’d strongly caution against pegging your career trajectory solely to a social media job title.

Pick Up the Phone – Stop hiding behind your computer. Business gets done on the phone and in person. It should be your first instinct, not last, to talk to a real person and source business opportunities. And when the Internet goes down… stop looking so befuddled and don’t ask to go home. Don’t be a pansy, pick up the phone.

Be the First In & Last to Leave ­– I give this advice to everyone starting a new job or still in the formative stages of their professional career. You have more ground to make up than everyone else around you, and you do have something to prove. There’s only one sure-fire way to get ahead, and that’s to work harder than all of your peers.

Don’t Wait to Be Told What to Do – You can’t have a sense of entitlement without a sense of responsibility. You’ll never get ahead by waiting for someone to tell you what to do. Saying “nobody asked me to do this” is a guaranteed recipe for failure. Err on the side of doing too much, not too little. (Watch: Millennials in the Workplace Training Video)

Take Responsibility for Your Mistakes – You should be making lots of mistakes when you’re early on in your career. But you shouldn’t be defensive about errors in judgment or execution. Stop trying to justify your F-ups. You’re only going to grow by embracing the lessons learned from your mistakes, and committing to learn from those experiences.

You Should Be Getting Your Butt Kicked – Meryl Streep in “The Devil Wears Prada” would be the most valuable boss you could possibly have. This is the most impressionable, malleable and formative stage of your professional career. Working for someone that demands excellence and pushes your limits every day will build the most solid foundation for your ongoing professional success.

A New Job a Year Isn’t a Good Thing ­­– 1-year stints don’t tell me that you’re so talented that you keep outgrowing your company. It tells me that you don’t have the discipline to see your own learning curve through to completion. It takes about 2-3 years to master any new critical skill, give yourself at least that much time before you jump ship. Otherwise your resume reads as a series of red flags on why not to be hired.

People Matter More Than Perks – It’s so trendy to pick the company that offers the most flex time, unlimited meals, company massages, game rooms and team outings. Those should all matter, but not as much as the character of your founders and managers. Great leaders will mentor you and will be a loyal source of employment long after you’ve left. Make a conscious bet on the folks you’re going to work for and your commitment to them will pay off much more than those fluffy perks.

Map Effort to Your Professional Gain – You’re going to be asked to do things you don’t like to do. Keep your eye on the prize. Connect what you’re doing today, with where you want to be tomorrow. That should be all the incentive you need. If you can’t map your future success to your current responsibilities, then it’s time to find a new opportunity.

Speak Up, Not Out – We’re raising a generation of sh-t talkers. In your workplace this is a cancer. If you have issues with management, culture or your role & responsibilities, SPEAK UP. Don’t take those complaints and trash-talk the company or co-workers on lunch breaks and anonymous chat boards. If you can effectively communicate what needs to be improved, you have the ability to shape your surroundings and professional destiny.

You HAVE to Build Your Technical Chops – Adding “Proficient in Microsoft Office” at the bottom of your resume under Skills, is not going to cut it anymore. I immediately give preference to candidates who are ninjas in: Photoshop, HTML/CSS, iOS, WordPress, Adwords, MySQL, Balsamiq, advanced Excel, Final Cut Pro – regardless of their job position. If you plan to stay gainfully employed, you better complement that humanities degree with some applicable technical chops.

Both the Size and Quality of Your Network Matter – It’s who you know more than what you know, that gets you ahead in business. Knowing a small group of folks very well, or a huge smattering of contacts superficially, just won’t cut it. Meet and stay connected to lots of folks, and invest your time developing as many of those relationships as possible. (TIP: Here is my Networking Advice)

You Need At Least 3 Professional Mentors – The most guaranteed path to success is to emulate those who’ve achieved what you seek. You should always have at least 3 people you call mentors who are where you want to be. Their free guidance and counsel will be the most priceless gift you can receive. (TIP: “The Secret to Finding and Keeping Mentors”)

Pick an Idol & Act “As If” – You may not know what to do, but your professional idol does. I often coach my employees to pick the businessperson they most admire, and act “as if.” If you were (fill in the blank) how would he or she carry themselves, make decisions, organize his/her day, accomplish goals? You’ve got to fake it until you make it, so it’s better to fake it as the most accomplished person you could imagine. (Shout out to Tony Robbins for the tip)

Read More Books, Fewer Tweets/Texts – Your generation consumes information in headlines and 140 characters: all breadth and no depth. Creativity, thoughtfulness and thinking skills are freed when you’re forced to read a full book cover to cover. All the keys to your future success, lay in the past experience of others. Make sure to read a book a month (fiction or non-fiction) and your career will blossom.

Spend 25% Less Than You Make – When your material needs meet or exceed your income, you’re sabotaging your ability to really make it big. Don’t shackle yourself with golden handcuffs (a fancy car or an expensive apartment). Be willing and able to take 20% less in the short term, if it could mean 200% more earning potential. You’re nothing more than penny wise and pound-foolish if you pass up an amazing new career opportunity to keep an extra little bit of income. No matter how much money you make, spend 25% less to support your life. It’s a guaranteed formula to be less stressed and to always have the flexibility to pursue your dreams.

Your Reputation is Priceless, Don’t Damage It – Over time, your reputation is the most valuable currency you have in business. It’s the invisible key that either opens or closes doors of professional opportunity. Especially in an age where everything is forever recorded and accessible, your reputation has to be guarded like the most sacred treasure. It’s the one item that, once lost, you can never get back.

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  • You Think You Can't Make Money While Pursuing Your Passion

    Twenty-somethings often think that their career is an either-or choice between fulfilling a passion or earning a lot of money, Dr. Meg Jay, a clinical psychologist who specializes in 20-somethings, told The Huffington Post. But 20-somethings should be looking for a career that can fulfill their passion <em>while</em> meeting financial needs. It's possible.

  • You Stay On A Path You Know Is Not Right For Too Long

    Twenty-somethings should be building a career that they want for the long haul, said Alexis Grant, an entrepreneurial writer and digital strategist. "If you realize you are not doing the right thing, figure out how to get on the right road as soon as possible. Don’t worry so much about lost time or lost investments," she said.

  • You Think 'I'll Really Start My Career At 30'

    Young professionals often think that the jobs they have in their 20s "don't matter," Dr. Jay said. But employees in their 20s should be in jobs that are helping them build "identity capital," so they can figure out where they want to be at the next stage of their career.

  • You Compare Yourself To Your Peers

    In school, students find themselves doing roughly the same things as their peers, which makes it easy to compare their accomplishments to others. But after college, comparisons are "just too complex to be useful," Dr. Jay explains. People also tend to only compare themselves to those who seem to be doing better than they are, which can lead to feelings of depression, she added.

  • You Act Entitled

    Twenty-somethings who had <a href="http://www.forbes.com/sites/susanadams/2012/08/02/the-biggest-mistakes-20-something-job-seekers-make/" target="_blank">over-involved parents can sometimes think that they deserve an easy ride at work,</a> Dani Ticktin Koplik, an executive and performance coach, told Forbes. This can have a devastating effect on their career, not to mention their relationships with superiors.

  • You Aren't Mindful Of Social Media Use

    Twelve percent of hiring managers said it's a mistake for millennial job candidates to discuss a job interview on personal social media sites, according to a recent survey by Adecco, a human resources consulting company. Not being professional on<a href="http://mashable.com/2011/06/16/weinergate-social-media-job-loss/" target="_blank"> social media can cost people their jobs</a> as well.

  • You Are Not Building Something For Yourself, Just Your Employer

    In today's working world, 20-somethings really need to be thinking about what they can walk away with when they inevitably switch employers, Grant said. "Throw yourself into your day job, but also build something for you because you will likely not be in your job forever," she said. Grant suggested writing a blog or working on obtaining a Twitter following.

  • You Worry Too Much About Current Work-Life Balance

    Young professionals will sometimes think that they are working too hard now and that it will be like that for the rest of their career, Dr. Jay said. What young professionals should really be thinking about is if they are in a job that will provide them with work-life balance in the future when they will be thinking about starting a family and other life decisions.