Absolutely it's pretty common during Covid for people to work from home. I would advise him to after every 2 to 3 hours he should get up from his sitting place and do any Physical Activity so that there should be adequate blood circulation throughout the body. Can do home workout at anytime of his liking for minimum half an hour . Should include healthy and balanced diet in your routine. Do yoga/ meditation early morning. It will help relieve stress.

Take adequate diet and plenty amount of water, so exercise every day and maintain social distancing and use mask

Daily 30 mins exercise. Healthy diet and meditation if possible.