So, whoever thinks he stands must be careful not to fall.--1 Corinthians 10:12, Holman
I think it's fine to feel good about it when you or someone you care about has done well. That's self-esteem. "I'm better than you. I won, and you're all a bunch of losers," is when it gets into sinful pride.
Another form of pride is failing to give God the glory. He is the one who gives us the gifts and talents that enable us to do great things. Gymnast Gabrielle Douglas knew this at the young age of 16. She won her gold medal and glorified the Lord right there into the microphone. Of course she was happy. She had done hard work to achieve what she did, and she had the right to feel good when it came out her way. But in her interview, instead of talking about me, me, me, look how good a gymnast I am, look how hard I worked and what I've sacrificed to get to this moment, she was all about Him, Him, Him.