[KerrAvon]

Well, there's also Dick Van Dyke, who's remained very physically capable as well as mentally sharp.

All of this varies, FWIW, with genetics and self-care. Over 30 is still pretty young, but nothing is universal; your heritage basically locks in your potential. There are chronically ill young people who feel much older than some 70 year olds.

Also, hearing loss is strongly correlated with loss of mental acuity and worse; hearing aids are essential if you have loss. Get your old self some current AirPods Pro.