This is so true when it comes to our own bodies as I have discovered during my life journey.
I was in my twenties and saw some of my work colleagues looking quite rosy cheeked and slightly breathless during a lunch break. Curious I asked what they had been up to. The reply came "Oh, we've been to a lunchtime exercise class". They explained a bit about the class and I decided to go along. (From what they said, it didn't sound that it was too strenuous, after all I did use my bicycle alot.)
Well, what a revelation that was!
The exercise moves were not difficult but the amount of aerobics was enough to make me feel slightly breathless or at least raised the pulse. I suddenly realised that I wasn't as "fit" as I thought I was. By that I mean that things that I could quite happily do in my teens (just because I was more active) were not as easy to do 10 years on. When did that happen?! The body doesn't send signals that it has changed - it had simply adapted to my lifestyle - which wasn't very active!
Surprised by this silent decrease in "fitness", I decided to join the exercise class. Gradually I saw an improvement - I could now carry on a conversation while exercising! Lunchtimes were actually fun!
Your body is your history. It is constantly adapting to what you are doing. It can become stiff and inflexible as you become less active or it can beome responsive and supple with increased activity. Research seems to be showing that a positive adaptation to increased activity continues even among the elderly!
Remember the body is designed for movement. If you've been a bit of a couch potatoe, you may be surprised at what you can't now do.
So maybe "you don't know you've got till it's gone". Get active, develope some body awareness. Give it time. It now seems that "it is never to late to start"!