I’ve always wanted to try a pomodoro routine consisting of working 30-45min, and then stretching / light calisthenics 5-10min. Ideally you’d exercise the muscles weakened from sitting, stretch the muscles tightened from sitting, get your heart rate up, and rest your eyes at the same time.
In theory, making a habit of this could drastically increase your level of productivity: you’re nullifying the adverse effects of sitting, getting your heart rate up, resting your mind, and improving memory consolidation  via immediate exercise post-learning. I don’t see why this wouldn’t enable you to study things for twice as long as you normally do. And 5min of exercise 5 times a day is going to give results close to one 45min routine (maybe 80% of total gains?).