I wouldn't change the topic! I'm having a hard time coming up with something and this is very good and unique. I think the Linsanity has died down to where you'd be pretty unique to write about him!
I consider myself to be pretty athletic and good at most sports. Before Jeremy Lin broke onto the scene, I was my own person and just considered a good athlete
These sentences drift away from where I thought you were going with your sentence about basketball. I don't think you need these two sentences
I was my own person and just considered a good athlete
I was just considered a good athlete
This stereotype was very uncomfortable for me
Why were you uncomfortable? (I know why, but you should state it/explain it)
I am proud to say today that Jeremy Lin is my hero.
Sort of contradicts the prompt. Maybe go with "I am proud to say today that Jeremy Lin is my hero... as long as no one else hears me say it."