If you're playing a lot of boxing games then a washable/wipeable cover for the Rift facial interface is essential for hygiene and protecting the Rift from sweat. I've got a couple of washable cotton covers from WidmoVR which I swap after each workout, or once a week if no workout, but others like the VR Covers products.
Also a thin head sweatband, and a fan pointed at your face really help manage the sweat.
Also a thin head sweatband, and a fan pointed at your face really help manage the sweat.