I remember seeing an Imax research paper on the net saying how to make a 3D effect from 2d pictures. I can’t find it at the moment, but a quick search found this: http://www.picturetopeople.org/image_effects/photo-3d-blocks/3d-photo-effect-creator-editor.html “By using this free online 3D photo editor, you can convert images into 3D designs that have high fidelity to the original pictures.”. I can’t say if the website is safe or not unfortunately, since I’m not familiar with it, but the point is that it can be done for single photos.
Another point is that I was told about ‘fitbit’ a month ago. From the website: “If you want to track your activity but don’t have a Fitbit tracker, you can use your smartphone to record basic stats like steps, distance and calories burned.” So it seems that you can have a wireless sensor that measures your rate of activity on a bike or on a treadmill, and you could (maybe) interface that with the VR set.