While you are walking somewhere, imagine that it is not you that moves, but the world that goes by. That instead of transporting yourself, you are turning the world over it’s axis so that the part of it you are more interested in comes closer.
It is easier to do when you are moving ahead, with few turns and no sharp ones. Try to feel, when you step, that you are pushing the world under you. You have to know, not fancy but know, that you are somewhere inside your head, completely still, watching something like a movie, a travel movie.
Pay attention to the fringes of your field of vision: the trees and posts move in an angle i find particularly conveying. If there are clouds or a beautiful moon, the sky is still and can make it easier for you to succeed.
The up and down movement of normal walking might be tricky to explain away to your brain. You might have to imagine the world as turning around a badly fixed axis, that oscillates with your impulse. But i, myself, usually just walk in a fashion that makes me move evenly (which is another exercise entirely).
Once you are getting better at it, you can try in a more difficult way. Stand, legs slightly spaced, turn your torso, and imagine you are rotating the world under you around an axis in the direction of your spine. Later, try having the same sensation moving only your neck.
Practice until the feeling becomes natural. You have to be able to do both kinds of movements (moving through and rotating) at the same time.
And the important thing about this is that it is true.
I mean, if there is such a thing as a true feeling, to feel that you are standing still while everything else moves is much more real than the way we are used to ascribe movement, because actually everything is always moving in relation to some referential system, and the only reference that is reliable is yourself. Even if it is not reliable, your own referential system is necessary, you need to use it, you have to develop reliable forms of compensate it’s bias instead of finding an perfect referential.
(But, to simplify, say it is true.)