Here's my advice:
Go into the dark at night. Basements, very dark rooms, etc. Think about all the worst things you can (for me, that'd be the Goat Man and skinwalkers) while you're alone and in the dark. Start with short periods of time if you have to--say five minutes--while you sit in the dark thinking. Do this frequently. When you're ready, repeat this outside frequently as well.
It won't be fun but I promise you it's the fastest way I can think of that will actually work.
