Mental Heath for long-term success in Academia
I suggest that you take up some stress reducing activity that you can perform for an hour or more several times a week. It shouldn't be a completely mindless activity or you may wind up just working when you should be giving your mind/brain a rest. 

Burnout is a terrible thing. 

On the other hand, periods of intellectual "rest" can actually enhance your work since the mind works on its own when you aren't constantly pushing the 'starter button'. 

There are a lot of possibilities for this. When in grad school I used to ride a bike with a group of mostly faculty members. We would ride at a fast pace for 35-50 miles a few times a week. The physical activity helped and we didn't talk math on the ride. The grad students I studied with had a weekly softball game for themselves and spouses. Nothing like a little competition. Something like Chess is fine for the mind part, but a bit of physical activity will keep you healthier. 

Currently I use Tai Chi for stress and general fitness (but not aerobics). The fact that it is a mind-body activity, not just body, helps give the brain a rest from whatever it is doing. 

Many people notice that they wake up with new ideas in the morning or after a quick nap. That is the effect of giving the brain a break. 

Stress can kill you. Find a way to do something (a) enjoyable and (b) not work related. Taking a walk now and then probably won't be as effective as an activity that does engage the brain but in a different way from the rigors of your field.