I encourage you to look into CBT. The best version of it I've seen is in the David Burns book "Feeling Good: The New Mood Therapy". Although you can also try a therapist (but they might be more hit/miss).
The basic idea of CBT is that our thoughts are a result of our actions, and by changing our actions we can change our thoughts. I'm not going to say it's super easy, but it definitely does work.
