<p>Nobody ONLY works and sleeps (for extended periods of time), so there’s certainly room to do more enjoyable things. How much time, though, probably varies widely from student to student. It’s one of those things that everyone needs to gauge for himself or herself, but fortunately, pass/fail is there to allow a lot of room for experimenting.</p>
<p>To provide some concreteness, though, I think that most students would have plenty of time to fit in jogging for 30 minutes and reading for ~1.5 hours everyday, if that was a high priority for them.</p>