Thanks you guy for all your ideas. I stand corrected, it's soccer, not football. (in VN, people always call it football, so I've mistaked all the time)
I can begin like this:
People may suprise to learn that I can play soccer well, although my outward may give them the impression that I am not a good sport player.
.......
then I will explain why I love soccer, how I love soccer, and what I learn from soccer (team play, for example).
Do I have to expose very clearly why it is a suprise? (i.e I'm small but run fast and my skills and movement are so...unbelievable. I think those infos are...absurd)
I don't tie it back a lot (it hard to do so in 250 words), but I will try to show my passion and some personal fact about me. Do you guys think it is okie?
(and also, any suggestion for another impressive opening)