Hi aspirant,

Now a days its most common among all the youngsters. The best way to avoid all those thoughts is, stay busy. Schedule your activities in such a way that, you never get time to think about all these stuffs. Try to be engaged in other activities and if you think you still can't handle these thoughts, consult sexologist. Never be alone, try to mingle with people, stay focused on your goals because, if your focused on your goals you can never come these kind of thoughts.

Hope it helps you.