My round is a little over six years old and I have old compact work which doesn't pay as well as my later better paid work; which often involves driving between jobs.
When my old work is due, I/we find it easy to take a day off, but when my new work is due; we're there no problem, starting as early as we can to pack it all in.
So for us, and other guys I've spoken to, money is a strong motivating force; just make sure you price well and you'll stay motivated.