There are the A things, the most important accomplishment in life. Procrastination is doing everything that is not them.
Good procrastination is when you are leaving of less important things undone (often things like errands).
Good procrastination is when doing things that will leave you better of for doing the A things (exercise, time off, wholesome food)
When I talk to people who've managed to make themselves work on big things, I find that all blow off errands, and all feel guilty about it. I don't think they should feel guilty. There's more to do than anyone could.
So someone doing the best work they can is inevitably going to leave a lot of errands undone. It seems a mistake to feel bad about that. I think the way to "solve" the problem of procrastination is to let delight pull you instead of making a to-do list push you. Work on an ambitious project you really enjoy, and sail as close to the wind as you can, and you'll leave the right things undone.
@paulg from http://www.paulgraham.com/procrastination.html