I seem to go through these fits of Just-Doing-It-Ness, usually brought on by a long bought of I'll-Do-It-Later-Ness. I've just finished a couple months of the Doing-ness and can feel a little of the Later-ness creeping around1.
I always hear people giving advice like "Learn to live in the now." Unfortunately it's just so easy to say "I'll live in the now ... tomorrow."
1For example, I almost cancelled this post and said "I'll do it later." I have to hurry up and finish so I don't change my mind.