Two quotations (from David Allen’s newsletter):
A task left undone remains undone in two places — at the actual location of the task, and inside your head. Incomplete tasks in your head consume the energy of your attention as they gnaw at your conscience. They siphon off a little more of your personal power every time you delay. No need to be a perfectionist, that’s debilitating in an imperfect world, but it’s good to be a “completionist.” If you start it, finish it — or forget it.
If you worry about everything, then you don’t have to worry about anything.