Some people remain very active and ambitious well in to advanced age, as long as their body and mind can hold out, which is something that will differ from person to person.
Here's a telling example: [1] In his 60's, Robert Owens was running marathons and undergoing Navy SEAL tests that would regularly crush 18-year-olds, and everyone he knew was trying to dissuade him from because they thought it would kill him. He still did it, and though he wasn't quite 80 at the time of the video and his body was starting to give out, he was insanely ambitious and accomplished at an advanced age, well past the point where most people would have thrown in the towel.
I've seen artists who are very active in to their 90's, and have heard of people running marathons in their 90's. On the other end of the spectrum, the rate of suicide, depression, and loneliness among the elderly is very high. That's not to mention the devastation of dementia and other mental and physical afflictions.
People deal with aging very differently depending on their body, mind, socio-economic circumstances, support networks, how they were brought up and their outlook on life, all of which vary greatly.