A sunny patch on the floor is enough reason to sit there for a while.

Small pleasures need no justification, and a sunlit patch on the floor is the clearest example. Nothing is produced by sitting in it, nobody is impressed, and it costs a quarter of an hour that would have disappeared anyway. Cats have this settled, while people argue with themselves about it. Warmth and light are reason enough to stop.

When you notice the sun has moved across a room, sit in it for as long as it lasts. Take nothing with you to do while you are there.