Compare yourself to yourself first. In other words, say you want to get in shape. If you keep comparing yourself to an olympiad you'll never get anything done. Start setting realistic goals and work towards them each and every day.
Get a lot of exercise and eat right.
Skip the parties for a little while. Wait till you get to the point where you are proud of where you are.
If you fall down, get up. Count to ten and start over again.
Have heros you look to for inspiration, but don't idolize them and realize that you can be powerful too.