Once I was talking to my dad and told him I had 5 minutes until a friend picked me up and didn't know what to do with myself. He said, "if you ever have 5 minutes to kill, go clean the toilet. You'll never be sorry." There are two ironic things about this story. First, my dad doesn't clean the toilets in his house (my folks have an arrangement where he does "outside" and she does "inside"). I don't know that he has ever cleaned a toilet, actually. The second irony is that apparently once in my life I truly DIDN'T know what to do with an extra five minutes. Crazy.
Anyhow, the point of all of this -- and the reason why I remember his advice, after all of these years -- is this: when you have a minute to spare, doing a small/concrete/completable task will ALWAYS be a smart idea. You could waste that time or you could do something useful that you will be glad for later (who's sorry that their toilet is clean? No one!). Some tasks don't take long at all -- but if you have 10 of those tasks to do, that time can add up. Scattering them throughout the day/week/whatever can really lower the stress level and the perceived amount of time it takes to get these things done. 5 minutes here and there? Do-able. 3 hour block of cleaning on a Saturday afternoon? Not nearly as fun.
Another point to make here - sometimes that 5-minute task can actually be something FUN! If you are really stressed, anxious, etc. -- taking 5 minutes to flip through a magazine, or sit in a comfy chair and look out the window, or take a few minutes to play with a pet -- those activities are valuable too.