Without writing a book about it I'll just say that I think the most important thing is people shouldn't look at this info and conclude that their body's going to fall apart no matter what.
I'm in my mid 40s and in the best shape of my life, lots of energy, aches and pains from my late 30s have all disappeared, to get there it took diet and exercise changes that were surprisingly modest. For me it was mostly weights, a little bit of cardio, and cutting back on my worst episodes of caloric excess.
I have friends who didn't do any diet and exercise interventions, and are starting to look like hell and complain about the "inevitable" consequences of aging.
And then there are those jacked dudes in their 70s who are hitting the gym 5 times a week, I can only aspire to be as healthy as them at their age.
Use it (with proper care and feeding) or lose it.