When something ends think about it as a time to reflect and learn.

If it was a good thing that ended look back over it and see what where the things that made it good and see if you could use some of those things in other areas of your life to improve them.

If it is a bad thing that has ended do the same, don't dwell on what happened, look at it with fresh eyes and see what lessons you learnt so that you can avoid the same mistakes again.