If you already have a schedule of exercise for a few days in the week, that is great! We suggest you do some activity on the other days, can be a light workout. A few examples are below so that you can see which best fits your situation:
Already working out in the gym (strength training) three days a week:
A key point here is to not overwork already trained muscles on consecutive days. Be smart about the choice of movements for your workouts. If you did a lot of lower body exercise on Monday, don’t do more lower body work on Tuesday. Also vary the intensity, if your 3 days at the gym are moderate/high intensity, then keep it light on the other days. Just a good brisk walk is adequate.
Already doing endurance work (like long distance running) 4-5 days a week:
Use the other 2-3 days to do light work that will help with your endurance work. Stretching and mobility work are good examples.
Doing high intensity training a few days of the week:
The key here is to mix up the intensity levels. As you are already doing high intensity work, use the other days to do some light work. Light here means that you are working at a level where you can still have a conversation with someone. Walking, stretching and mobility work are good examples and will complement your higher intensity days.
Want an idea for an exercise that can be done either at low, medium or high intensity, to work on flexibility and strength? Check out the Surya Namaskar.