Sweat Management (And why I don't use a waterproof VR Cover)

LepperMessiah1

Sweat is probably the single greatest deterrent keeping VR from becoming an optimal vehicle for home fitness. Not only is the breathability in an VR HMD relatively poor, but the headset itself emits heat, making the situation worse. Having a sweaty face is one thing, but if that sweat manages to find itself into the inner workings of the headset, you could have a real situation on your hands - or heads. Rather than attempting to make the headset sweatproof with something like a waterproof VR Cover, which will effectively just redirect the sweat elsewhere - potentially into the headset - a better solution is focusing on sweat dispersal.

The foam gasket is actually pretty absorbent, and if thoroughly rinsed out and line dried after a workout session, this is going to be your best first line of defense against sweat accumulation.

Here's what else I recommend:
Crank the AC
Wear breathable clothing, preferably polyester or some other breathable synthetic
Point fans into your play space
Wear a cotton bandana
Wear a sweat band over the bandana
Use earbuds or speakers instead of over-ear headphones.

VRHockey

That last one is a huge tip. I use over-ear headphones when I stream and with a Vive it can build up a decent amount of heat without too much activity.
If you have to use over-ear headphones try to give it a bit of space between the top of your head and the top of the headphones. The extra pressure and layer of padding helps trap more moisture in an already moist area.