Write software to ship. Even the "farting around" stuff. Document, test, READMEs, etc.

Seriously. It really helps to power through the "ho-hums."

I have found that the reward of a finished product, at the end, works well as a "carrot" for me.

Also, as has been mentioned elsewhere, establishing habit is, in my opinion, essential.

"We are what we repeatedly do. Excellence, then is not an act, but a habit."

- Somewhat incorrectly attributed to Aristotle