Physical exercise

Do you know of any ancient-or-modern formally-Buddhist sources which recommend personal physical exercise -- for physical and/or mental well-being? Because I'm not sure I do, except only maybe very tenuously: - to help stay awake - walking as a side-effect of the alms round - East Asian abbots, might be inclined to include work in the daily routine. It seems to me that exercise is recommended and beneficial -- from personal experience, and according to modern medical propaganda. So maybe it's surprising if it is nowhere in Buddhist doctrine -- including for lay-people?