[mini61426]

How can you stop be in love with a man you know you shouldn't be in love with how can you not think at him so often.. I can not avoid him I work with him everyday

[DoulaLC]

If it's a relationship that can't be acted upon, then you have a few choices... if possible, be moved to another department or area so you don't have contact, or contact is very limited. Immerse yourself in work and social activities where he is not around... take on additional jobs that you have to focus on, go out with friends, etc..
If you are married, spend time working on your marriage, develop a new hobby with your partner. If this man is married, and you are single... have your friends fix you up, join a dating service, join a club or group of an activity you've been wanting to try that you can meet people through, etc..
In time, thoughts of him will tend to fade... not quickly, but it will happen. If it comes down to it, a job change may be necessary... fresh start, clean slate.

[JBeaucaire]

Being grownup means you ABSOLUTELY have to do right in situations like this. The heart is a cruel taskmaster.

NO JOB is worth this sort of temptation. Unless you are 100% sure of yourself and your ability to handle, keep the feelings in check, etc, then change jobs.

Don't dismiss that idea out of hand. There are millions of jobs. The awesome job you love is not unique, it can be replaced and your character preserved. If necessary, you must consider and perhaps even do this.

You can't control your heart, but you CAN control your time and actions. Give up now on "getting over"your feelings. You didn't CHOOSE to be in love with him and you can't choose for it to go away. But you can involve your mind endlessly in other activities. You can make/refer to lists outlining the intelligent reasons you have to ignore those feelings/thoughts.

Until something else comes along in your life to fill that slot, you're going to keep thinking about him. Distract yourself with other activities and make sure you are giving yourself plenty of chances to meet and get interested in other men.