I've found this to be a very important factor in my exploration in internal training.
Watch this video until some of what Feynman is talking about sinks in. (pun intended)
Try this experiment:
Stand, move, walk around, do some aikido movements, and imagine yourself standing on the ground. You're a big strong tree with roots going way down - at least as far down as you are tall. Just notice the feeling, the texture of the movements and your body. Pay attention to where the weight seems to be on various body parts. Do that for a few minutes.
Then, try this. Completely disregard the ground. The earth has no power whatsoever. Remove your attention from it. Place your attention upwards - to the sky and to the air around you. Feel yourself in the air. Imagine this time - rather than standing - that you are falling through the air. Stand, move, walk around, so some aikido movements. Notice the feeling, the texture of the movements and your body. Do that for a few minutes.
Looking forward to some feedback on the experiment, and some discussion on the principles and change of attention. Cheers...