Putting it off

Why do people procrastinate? Laziness, fear, uncertainty? I can understand that putting off the big things is easy to do. Huge tasks can seem insurmountable unless broken into small steps, but what excuse for the small stuff? What holds me back? Why don't I just pick up the phone, pay the bill, load the diswasher? I want to, but yet my ability to avoid often small and mundane things amazes me. Why do it? Why not just get up and get on with.....Is blogging simply another distraction from reality?