I ran across something I wrote in an email to a friend years ago, about how we become gradually more self-centered, more blind to the real world (and people) around us, as time goes by:
<<I thought of the wife’s line from “The Death of Ivan Ilych” (approximately): “He screamed for two days. Oh, how I have suffered!”
There’s an object lesson here about how it gets harder and harder to respond to grace and be transformed by Christ. We might have been well able to feel jostlings of conscience and jostlings of compassion when we’re younger, but with each passing year it gets harder for new thoughts to break their way into the fortress.
I think most people these days are living wholly in their heads, and only occasionally being jolted into direct contact with reality. All the mind’s a stage.
The thing is, this gets worse the older you get. You become really imprisoned in your mind, the mind you have arranged and decorated the way you like it for all those passing years. It gets harder and harder to apprehend reality.
That’s why so much of the Orthodox way is concerned with getting out of your mental captivity and into reality. There you can see other people, and respond compassionately. A person who rigorously arranges the world to accord with what makes him comfortable can get to a point where he is finally blinded, and it is too late.
“Lord make me chaste, but not yet” (as St Augustine said) is a dangerous game; you don’t know when the point will come that you cannot see that this is happening to you, when you have no ability to understand what you are losing. Drifting away in an unmoored boat, and yet fully entertained and consoled by your familiar daydreams, arriving at death sealed-off from real life and numb.>>”
I would suggest that keeping the body limber is closely associated with the ability to change our minds. Prostrations and fasting, crossing ourselves, smelling incense etc all empower us to repent.