Procrastination and Boredom

My job isn't terribly difficult. Most days, I should be able to get everything done that needs to get done in less than 1/2 of a workday, and yet still I procrastinate. I'm not sure what the problem is. The tasks I need to complete aren't boring - not exactly. My gut instinct is that it has something to do with poor self-esteem and lack of confidence, as in I put things off because in my heart of hearts I feel like I can't do them effectively and no one takes me seriously as a manager.