B.K.S. Iyengar sums it up this way: 

“ Even as the body ages and is able to do less,
there are subtleties that reveal themselves,
which would be invisible to younger or more athletic bodies.
You have to create love and affection for your body,
for what it can do for you.
Love must be incarcerated in the smallest pore of the skin,
the smallest cell of the body,
to make them intelligent so they can collaborate with all the other ones,
in the big republic of the body.”

— from Light on Life: The Yoga Journey to Wholeness, Inner Peace, and Ultimate Freedom