Running is terrible exercise. Terrible because it’s extremely hard on the body unless you’re on the lower end of the BMI scale. If you do any sport with a high mobility requirement, you can feel how tight a single run makes you.
The killer in old age is immobility, of your knees and hips. Running really doesn’t help.
Now before people point me to some article debunking how running isn’t in fact bad for your knees, that’s not what I’m saying. Efficient running is all about maximising power through a very small range of motion. Runners by and large have terrible hip mobility for athletes.