Becca, I talk to myself all the time- specifically when I'm trying to work out complex problems in my life. And honestly, I feel like my thoughts are deeper and more meaningful when I "release" them from my head. I wouldn't worry about it too much. Unless you start losing jobs or feeling like there is literally no one on earth you can talk to, you should be okay. Keep the self-dialogues rolling!
It sounds like you are very restless and you need to move to think. Sometimes when a person has a lot on their mind they might talk out loud because it is too noisy in their heads. I am not sure what problems you have or believe you have but it sounds like they are weighing heavy on you.
This is nothing in itself to worry about but it can become a habit. Have you tried journaling or keeping a diary to throw your thoughts down on?