There's no tip to stop this feeling! It's unstoppable! I don't think it's forbidden for you to be into your co-worker. If you like him that much and there's indeed an attraction between you, then why not look into it and try to work things out! You never know where this can lead and it might be good. You'll only if you try ;) Good luck!

I agree with Kelly, if you are attracted to him you should let him know. Be confident and unattached to the outcome and who knows he may just be that into you! Good luck!

If you are certain you want to stop the feelings, then you need a distraction. Change up your routine so you don't pass by his desk as often. Come to work a few min early so you aren't sharing the elevator in the morning. And find something fun to do after work that you can do and keep your mind off him.