What is the easiest way to move on in your life from a guy?

I found myself okay with everything and I was fine that he and I weren't friends anymore after many many years of friendship and several relationships. I miss who he was not who he is now and every time and again I am saddened by the thought of what used to be. I know that my life is better now without him and he has made me stronger but I cant help but to look back at times