Remember the time to relax is when you don't have time to relax.
For Wellness Wednesday, here's a stretching video that my teens and I like. Only five minutes long!
Doing a brief stretch like the above fits in really well if you are doing the Pomodoro Technique. My oldest offspring gets the credit for introducing our family to Pomodoros. Have you heard of it? You work intently for 25 minutes (on whatever) and then take a 5-minute break. Working with intent can help you focus better, and taking regular, timed breaks can help you be more productive (and keep you from getting stiff!).
Here's an online Pomodoro timer, in case you want to try it. (You can change the time lengths if you want, elsewhere on that site.)