Ugh I am in this exact situation right now and it sucks.
But I just try to think about the things I dislike about him, the things which would really bother me, like:
1) He has a bit of a weird nose (actually ok I don't mind that)
2) He's a little bit skinny
3) He looks gay
4) It wouldn't surprise me if he's actually gay
Yeah ok, that doesn't work particularly well because I still really like him.
But they say that time is a healer, and one day you'll wake up and it will be a little bit easier, and the day after that it will be easier too.
Alternatively, try concentrating your efforts elsewhere, distract yourself.
Or, y'know, alcohol. Always works in the short term.