Self-esteem is the way you think about yourself and what you expect of yourself. The foundation for positive self-esteem is built at an early age and is influenced by relationships between you and your family. Your feelings about yourself will change as you grow. Praise and criticism from parents, friendships at school and attitudes from teachers will continue to affect you from preschool through high school. Persistent criticism, teasing and failures can make you feel worthless. Praise, support and finding something you are good at can help you develop confidence in yourself.

That confidence, or lack of it, may affect decisions made during puberty. All kinds of peer pressure and outside influences can guide you as a teenager and affect your decision making process. The depth of your self-esteem also affects those decisions, whether it's about playing one sport over another, who to hang out with, which electives to take in school or other situations such as smoking, drinking, or deciding to have sex.

Boosting Your Self-Esteem
As your body changes, you may feel unattractive, awkward, even ugly. But believe it or not, you can change the way you feel about yourself — and the way other people perceive you — just by changing the way you think about yourself. First of all, if you are worried that your weight, height or anything else is unhealthy, talk to your health care professional. If everything is okay physically, then you can begin dealing with the image problem.

First of all, accept the fact that there are many things that make you a unique person — your eye color, skin shade, height, facial shape — cannot be changed. And note, as you watch television and movies, or people-watch at school or the mall, that attractive people come in all colors, shapes and sizes, that girls and women who are not supermodels are, in fact, loved and adored by the opposite sex.

If you do want to make a change, such as losing weight, don't set unrealistic goals ("I want to be a size five," or "I want to lose 50 pounds in three months.") Instead set realistic goals you know you can achieve, such as exercising three times to five times a week and eating well. The pounds will come off and you'll enjoy a feeling of success each time you meet your goal.

Next, the most important thing: When your inner voice starts putting you down, counter those comments with positive or neutral ones.

• Replace "I'm fat" with "I exercise and eat right."
• Replace "I bombed on that test; I'm just stupid" with "I'm smart and I can do better. I'll ask for help if I don't understand something next time."
• Make a habit of complimenting yourself: "I'm good at math ... I'm really funny sometimes ... My hair looks just right today." Don't worry that you'll become conceited. Because we all have a habit of focusing on the negative, these thoughts tend to just balance things out a bit.
• At the end of the day, think about three things that were good about the day. Maybe you heard an old favorite song on the radio, or polished off a good book under the shade or knew the right answer in class. It's a rare day that doesn't supply us with something that makes us happy — the hard part is being aware of that something.