Which VRCover did you buy specifically for sweat? I bought the memory foam soft cotton one (it's supposed to come in tomorrow" because I wanted to to be washable, but also comfortable in other scenarios, though I very much have the same experience as you described and I'd like to make exercising with VR games a much bigger part of my routine.

Edit: I'm mostly curious about the "leather" ones as they sounded uncomfortable for other usage, but specifically aimed at physical exertion.