If you have a liking for the first one, why don't you write about it and try to weave painting and Yoga into it? You can say how painting and Yoga helped you overcome your hardships, how they drive you and inspire you, letting you look at problems from different angles etc.
If these things are a huge part of your life, I'd include them all. 500 words aren't that few. You should try to tell as much as possible about yourself, so if I were you I wouldn't limit myself to just one thing. Especially if you're thinking about throwing out things you're passionate about =) When people write about things they care about it always turns out more vivid.