It depends, of course. If you are single, you can do whatever you want, organise your time, etc. In general, you should limit yourself, pace yourself, take time for physical activity and, most importantly sleep and eat right (meaning: 7-8 hours per night and according to your diet – you should have normal BMI, for lack of better measure).

If you are in any kind of relationship, with children, etc., then of course you have a different thing at your hands. Basically, you have to follow the same general rules as above, but following them will require crazy amounts of discipline and compromise. And of course, learn to say “no” and good luck!