Taking the time to grieve over the loss of your relationship and the person you gave your heart to.
Then going back to doing things that you love or make you happy (writing, artwork, etc.)
I also find it helps to not spend too much time alone once you've had your mourning period. Be with family, friends, people who can make you laugh and just get out of the house, even if its just for a short while.
Get back on the horse so to speak. Even if it's just meeting someone for coffee, it's better to get back out there and move on. Not saying you should do this right away, but not to let too much time go by where all you do is sit around and think about the ex. They've moved on with their life, you need too as well.