I do this a lot. I am always obsessively thinking about something -- previous relationships, loneliness, career issues, etc.

I kind of started the other day by just ignoring those thoughts. I realize they are a thought because I over-think and my mind is making things look more bad/difficult then they really are. Example -- I am always thinking about a previous relationship that I screwed up... by just wanting to be alone sometimes and withdrawing. It was an amazing relationship - I am not generalizing. Everything about her is what I've been looking for... I can't explain it. I will always think "Will I ever find someone like her? Will I find someone that is enthusiastic about randomly finding a dog show like she was? Will someone have a really awesome Dad that has a party every year? Will her Dad shake my hand 100 times? Will I feel accepted by her family? Everything I explained was my relationship. I never had a Father figure. Meeting her Dad was amazing. The party he has is amazing. They take a vacation every year to the beach. I ask myself will I ever find that again? Then it's a spiral of thoughts. I recognize the thoughts, I understand they are there, and I let them guide me. I say "You know what? I will do my damn best to find someone like that again. I will find someone I am truly happy with again. I will become the better person for myself, my girlfriend/wife, and my children." Then I feel happy again. I feel motivated. I recognize that my relationship isn't a loss -- it's my gain to be better than who I was, and to also find someone I truly love being with, and being happy in the future.

So look at everything as a lesson. Realize your emotions are there for a reason... they are just like a physical pain when you tough something hot. They are telling you something, and guiding you something. Maybe you have obsessive thoughts about something that is unfinished business? Your thoughts and emotions are a call-to-action. They are a life-lesson.