You can look in to meditation and DBT techniques. There are a lot of free sites out there and Yahoo offers a free DBT class. They both attempt to teach you to focus on the moment, not to worry or obsess about the past or the future since there's nothing you can do about them. It's not easy; it requires a lot of work, but it does help to at least some degree and is definitely worth a try. PM me if you need more info.