There is always some contradiction between our desire and what we can do, between how we want to use our body and then some signal of pain warns us "No you can't do that!" There are limitations.
When you are a kid you have to discover all these things, what your limitations are....I learnt that I could not walk on water, I tried it but I couldn't do it! I tried all kinds of things, I tried cross a great canyon by hanging on the washing line but that also didn't work! I crashed in the great canyon, almost broke my back!
So one learns the limitations of the material energy
(Kadamba Kanana Swami 21/06/2004)