It’s not like you can choose what to feel; it’s your heart that made the decision. But you can control it. If you keep talking to others about him, or thinking of him, then you’ll like that person even more. Instead, just distract yourself.
Do something you like first before doing something you’re good at. But if you’re bad at the thing you like, then it won’t work. Just trying to do what you’re good at, there must be a reason why you’re good at it and by doing it often; you’ll grow to like it.