Resistance and Inertia at the physical level

Q: Today I tried to take a walk. It was so tiring that my right leg ached! I had to suspend my normal painting work! All this in spite of my having used will-power.

In the body there is a strong resistance of obscure inertia and this inertia is always accompanied by an openness to contrary forces. So as soon as you put your will on it the contrary reaction is suggested by the lower forces and through habit prevails. I don’t see anything to do but press on with the progress of the inner and higher consciousness till the body is obliged to open to it.

–  Sri Aurobindo