I think of it as scaling a mountain. When you're at the base the mountain looks imposing and out of reach. As you begin the climb it's hard work and you don't know your way around and feel lost, and every time you look up the mountain remains as imposing as before. But then you begin to make progress, and the mountain begins to seem smaller. Now you can finish the climb because it doesn't seem like that much more work -- you've done the truly hard part, which was: getting started.

Admittedly when I'm at the base I take my time getting started. But once I'm started, I can power through.