Actually, there's nothing else you can do. You don't have time. My experience is to massage my abdomen before going to bed every day, that is, 60 times clockwise and 60 times counterclockwise. Too little doesn't make any difference, and 80 will do.

Because sitting every day, the abdomen is easy to get fat. Be sure to go out for a walk after class, get some fresh air and keep a clear head.

There is also a long time to brush your teeth, and your neck and shoulders can move a little.

If the school has stairs, you should walk more after class.

I wish you good health and progress in your studies.