What I’ve found that helps me with this is follow through on the worry. For example, maybe I’m worried my boyfriend will leave me, and to follow through on that I think “then what happens?” Well, I would be depressed for awhile, and then eventually get over it. I’ll go through the stages of grief for the death of the relationship but I will survive and move on. This Follow Through thought pattern works best on situations you have actual control over in your day to day life.

Another thought is “you can’t control everything but you can control how you react to things”.