You just answered your own question. Get out, keep yourself occupied. Sitting at home thinking about shit will send you nuts. It sounds like you have way too much time on your hands. Get outdoors and get some air and clear your mind, 'cause there is nothing wrong with you.
We all think about shit, but it's how you deal with shit that matters. You are not dealing with anything by sitting around moping. It's all about having a positive mindset, because i can tell you know, chicks and people in general can pick a negative, pessimistic attitude from a mile off and people don't want to be around negativity.