The human body is an amazing piece of engineering. Even now, medical science is just scratching the surface.
A mark of good health is that when you're in the prime of life, you don't necessary notice your body. It doesn't draw attention to itself. Rather, it's something you use to do things.
An exception would be athletes who push their bodies to the limits. I don't know this for a fact, but it wouldn't surprise me if women are more apt to notice aging in terms of their changing appearance while men are more apt to notice aging in terms comparing what they can do in middle age to what they could do in their teens and twenties. Even if they can still do the same stuff, physically, they can't do them as easily or as well.
Age and ill health makes us aware of our bodies. When everything is working the way it was designed to work, it's easy to take things for granted. It's only when things begin to break down or malfunction that we realize how much we took for granted. Simple, mundane things we never gave a second thought to.
Without suffering, we're like thankless thoughtless children who just assume their parents exist to cater to their every whim. Aging and ill health reminds us that we're not gods. We're not immortal. Our well-being is often dependent on things beyond our control. And as time wears on, we begin to lose control over things we used to have some control of.
This is a stimulus to make unmindful and ungrateful humans appreciate their utter and ultimate dependence on God. Life is a gift. Your body is a loaner.