THE BLOG
12/20/2013 04:58 pm ET Updated Feb 19, 2014

The End of Fitness Plateaus!

Co-authored by Andrew Heffernan, co-author of The Exercise Cure (Rodale, 2013).

As a lifelong fitness enthusiast and a career fitness professional, I've seen a lot of trends come and go. Superslow training. Balance training. Step aerobics. Tae Bo. P90X. Spinning. Rowing. Nordic-tracking. The list goes on and on.

Ever notice, though, that these trends typically have about an eight-week shelf life?

Sure, you may see them straggling along past the eight-week mark. But how long does your average person do Step, or Zumba, or P90X?

The answer? Eight weeks. For eight weeks that's all they'll talk about: the new Zumba class. The new piece of exercise equipment they got for their garage that solves everything for them. You'll probably even notice them getting slimmer or muscling up a bit. But soon enough, the talk will end. The membership will expire. The equipment will start to gather dust.

How soon? Eight weeks. You can set your watch by it.

Funny thing: Eight weeks is ALSO about how long people continue to see results from ANY exercise program. Even the spiffiest, coolest, most bang-zoom-wow program you can imagine, promoted by the slimmest, sexiest, most six-packed stud or studette in the world. That's about how long a body can adapt to a new stimulus before you need to shake it up with something new. I've seen this happen over and over with my clients.

So every eight weeks, I shake things up. Radically.

You should too.

If you go to the gym, you've probably seen this trend at work: the guy or girl who slavishly does the same workout for years. You may have even thought to yourself, "Wow, wasn't that guy curling or benching or squatting that same weight two years ago? Poor guy," you think, "Spinning his wheels, going nowhere, hoping that the honeymoon phase when he was making real progress will magically come back again."

And then you realize you've been doing the same thing.

But rather falling into the fitness doldrums (and getting bored, and probably taking an extended break from training) you can use this one little tidbit of fitness trivia to help you stay on a constant upward-spiral of improvement.

The solution: Every eight weeks, choose a new goal: Lose 10 pounds. Gain five pounds of muscle. Lift a Volkswagen. Run a marathon. Or just keep up with your kids. You want to make it YOUR goal, not the goal of the exercise addict next door or the infomercial yelling at you from your blurry TV screen. Make it a goal that speaks to YOU, something tangible and attainable that you're passionate about.

If you have a longer-term goal -- say, lose 50 pounds or add 100 more pounds to your bench press -- break it down and attack it in eight-week chunks: Focus on building a cardiovascular base for eight weeks, then work on sprinting. Work with low reps on your strength training, then higher reps.

Maybe you need a coach to help you. Or a decent exercise manual (the book that Andrew recently co-authored, The Exercise Cure, has just such a program!). Or a knowledgeable training partner. Any way you slice it, do it, and do it hard.

For eight weeks.