Most Helpful Guy
Time and keep busy. Don't sit around giving yourself time to think about him, work, go out with friends, whatever you need to do to keep your mind off it. In time, it will get less and less until no more.
Most Helpful Girl
Give it time. It's cliche but it really is the only way. Time will make you think of him less and less. But you HAVE to delete his number, cut of all contact and block him from social media. Do not media stalk. This is unhealthy and only causes you to keep thinking of him and being reminded which will hinder the natural healing process of giving it time.
Focus on you and what matters to you. Discover yourself. Read some good break up books and join a only community like love shack. There are so many support communities out there.