I posted Why is exercise good for you? But I wanted to dig a little deeper into one specific point. I can grasp the concept that the body responds to the microdamage of exercise by building up the muscles/tendons to be stronger and better able to withstand future exercise. So it makes sense that a suitable level of exercise done in a safe manner would be good for your body's overall health.
I can accept that this continues to hold true when sustained over many years, even into old age. But I've also heard that there are some parts of the body which don't respond to exercise in the same way that muscles do. For example, I heard that cartilage in the knees will slowly erode over decades of life and will wear out faster with heavy use. I have long legs and an older tall guy once told me to take care of my knees. He said he used to play a lot of basketball but had to stop because it ruined his knees.
Another example would be back injuries like a herniated disc caused by improper heavy lifting. You can read about how Christian Bale suffered a herniated disc just from gaining 43 pounds (19.5 kilograms) and adopting bad posture for his character role in the movie American Hustle.
So it seems like there are certain parts of the body that respond well to exercise, and other parts of the body that we should try not to strain too much. I am wondering about the difference between parts of the body that repair their own damage and other parts which just wear down and never repair. If the goal is to gain the health benefits of exercise, how do we do that without also getting the harmful effects? Like doing permanent damage to your body that will not heal, or slowly wearing out important areas like joints over the decades and leaving you debilitated in your old age?
One approach I tried is to avoid "high-impact" exercise like jogging and instead I got a rowing machine which I understand is easier on the knees and ankles. I wonder if there is someone who knows more about parts of the body which do and do not regenerate well, and how to exercise in a way that provides the benefits of a workout without doing lasting damage to their body. Maybe there are some users here who are in their 60s or older and have found good, sustainable workout practices?
I am aware of this question: Do joints wear out from exercise? But I would like ask in a more general sense about how to develop a healthy workout routine that can be sustained for many decades while avoiding not only joint injury, but also back injury and indeed any workout-related injuries or ill physical effects in general that can develop over the years.