All you can do is fill your day with positive things and deliberately visualise a positive outcome. Don't let the balance of your life become tipped over to where techniques take over from your normal daily activities.
Trust me, it really isn't worth it to cry over someone. I'm not being harsh, I've been there and realised what a waste of time it was, when I could have been doing something I like, been out with friends, even spending time with my cat. Much better than crying, which is unproductive.
Or are you crying all the time because of other issues? Depression or anything else? Really think about it.