I'm working on my Happiness Project, and you should have one, too! Everyone's project will look different, but it's the rare person who can't benefit. Join in -- no need to catch up, just jump in right now.
The subject of self-esteem is a topic that has generated a fair amount of controversy over the last few decades, but one thing seems clear: you don't get healthy self-esteem from constantly telling yourself how great you are, or even from other people telling you how great you are. You get healthy self-esteem from behaving in ways that you find estimable.
In other words, the best way to feel better about yourself is to do something worthy of your own respect: keep a difficult resolution, meet a challenge, solve a problem, learn a skill, cross something unpleasant off your to-do list. And one of the best ways to feel better about yourself is to help someone else -- do good, feel good.
I had a friend who went through a period of tremendous rejection: she was fired from her job, she didn't get into the graduate program to which she'd applied, and her boyfriend broke up with her. Everything worked out fine in the end, and I asked her how she got through such a tough time. She said, "I was practically addicted to doing good deeds for other people. It was the only way I could make myself feel like I wasn't a total loser."
I recently performed a very small action that gave me a big boost: throwing away other people's trash. I've always been careful to throw away my own litter, but it never occurred to me to do anything about random litter lying around.
The other day, though, I was in the subway, where an empty Snapple bottle was rolling around to the great annoyance of everyone in the car. The bottle rolled back and forth, back and forth, and I thought, "Someone should pick that up." Then I thought - "Someone like me! Why shouldn't I be the one to pick it up?" So I did.
I was astonished by the surge of good feeling I got, quite disproportionate to such a minor action. I also thought I could feel a palpable wave of approval from the other people on the subway - which I was probably projecting, but which also shows the effect that my tiny good deed had on me.
Since then, I've looked for chances to throw away other people's trash. In a coffee shop, I threw away the coffee cup someone left on a table. I threw away a plastic cup that was rolling down the sidewalk. Etc.
So try it yourself; throw away someone else's trash. "Do good, feel good" is a happiness truism that really is true. Act like a considerate citizen of the world, and you'll boost your self-esteem.