I'm not sure if this works in the day-time, but either way it definitely helps to have clouds. The process is simple. Go outside to an area where you aren't going to run into something (like a field) then start walking. Now tilt your head back until all you can really see is the sky. Because of perspective and because the sky is so far away, it doesn't appear to move at all. Your brain is now receiving mixed messages, because your body is telling you "yes, you're walking" but your eyes are saying "you're not going anywhere". It's not exactly epic, but it's worth doing at least once.