For me, a stable job is key. The structure and accountability makes it hard to fail, and my (relative) lack of ambition ensures I don't over-commit or stress too much over work. It's everything else that I get lazy about! I have plenty of time, but it's too easy to do fun but unproductive activities.

If something doesn't trigger my "oh no, this will lead to more responsibility" alarms, I can be very productive. For example, I love to plan a trip, because it has a discrete start and end and is entirely within my control.