Craig Weiler has the answer:
You have one set of teeth, one set of knees, one set of lungs and one back. If you don’t take care of them, you can’t re-boot. You can get knee replacement surgery and you can get your teeth capped and wear dentures, or get new lungs, but it’s not the same as your originals. The back is much more tricky and if you damage it enough you’re never coming back from it.
You have one set of hands and feet. They are irreplaceable as is your brain. So if you damage them you’re never coming back from it.
Your body, in other words, is a one-off. You will never have another one as long as you live. If you start taking good care of it and you’re mindful in your 20’s, you’ll be far healthier and happier in your 50’s and beyond.”