Not a popular idea, because it doesn't necessarily sell well, but I believe meditation is the most important exercise you will ever do, and if you skip a day, any other exercise you do that day will have a diminished return on your time invested.
Stress is the number 1 killer on the planet, stop pretending like it isn't.
Here's a free guided meditation:
___Sit down, BE quiet. For a little while just BE.___