mourning change in life..How do you get passed it?

Coming to terms with the fact that things change is so hard to do at times. I'm not real good with change. People change, relationships change, and sometimes you grieve over the past relationships and people and the way they use to be. I've decided that I grieve hard, very hard, and long too. I view change as pain. Always thinking the worst. I have to be reminded from time to time that change doesn't have to be bad, but can actually be good. First one needs to get to the acceptance part, be willing to let go some times and move on. Where is the magic pill that gets you to that part?? Why do I always accept, then take it back?