Most days I am so tired by the end of the day from work and chores that I find myself not having the mental bandwidth to think of anything elaborate to work on. I like to keep a regular art habit though, and figure drawing seems to work out best. There isn't a whole lot of decision making on what to draw or paint (hubby chooses one or two pictures for us to work on), and keeping the tools simple (pencil and artgraf, or monochrome watercolor) makes it simple to setup and tear down.
The other advantage of doing these simple figure drawings is that it affords me an opportunity to think of ways to compose an interesting picture by manipulating the value patterns, while keeping most of the other parameters constant.