I have seen a lot of people age a decade or more in just a few years.
Aging has less to do with physical and more with mental. I have had years when I did not slow down at all. In fact, often times I was doing better years later than when I was younger. Times when I aged quickly ... during messy divorce, job loss, accidents that caused significant damage. Some were reversable, some were not. My limitations today are 80% mental and only 20% physical.