Self-esteem is huge. It affects so much of who you are and how you act. Imagine the behavior that would result if deep down you felt you were bad, or inadequate, or incompetent, or unattractive, or unworthy. You'd be very sensitive to criticism, you'd second-guess yourself, decide not to try things, feel lousy about yourself all the time, so relationships would be very difficult. Many psychological disorders sprout from low self-esteem. It's a problem with a lot of people, baggage from growing up, it can be the result of adults putting us down when we were kids, always feeling inadequate.
It's hard to turn this around, but it can be done. The key is to give yourself credit for any good thing you do...small or large. It's like making deposits into a bank account...your repository of self-esteem. You say to yourself, "I did a good thing, I'm pleased with how that went." Maybe you just showed up on time and made a contribution to a group effort. GIVE YOURSELF CREDIT. After a while you can "draw interest" on this account - in the form of self-esteem. But many people "discount" amazing accomplishments. I knew a gal who was disgusted with herself because she came in second at the state championship swim meet. And a guy who got a Bronze Star in Iraq and said "it wasn't anything." COME ON! You see how low self-esteem feeds itself? It's obvious, if you never give yourself credit, you can never draw the interest.
So you see, you have to do this for yourself. It's great if people don't abuse you verbally or put you down. But in the end, YOU have to give yourself credit, build up your own account over time. All that praise and rewards from adults "just because you're you" is shallow BS and doesn't work. A smart kid knows those tokens are meaningless and may even feed low self-esteem.