Doubting what you see is a very odd experience. And doubting what you remember is a little less odd than doubting what you see. But it's also a pretty odd experience, because some memories come with a very compelling sense of truth about them, and that happens to be the case even for memories that are not true.
Daniel KahnemanEvery night for the next week, set aside ten minutes before you go to sleep. Write down three things that went well today and why they went well...Writing about why the positive events in your life happened may seem awkward at first, but please stick with it for one week. It will get easier. The odds are that you will be less depressed, happier, and addicted to this exercise six months from now.
Daniel Kahneman