The thing is, its all just a theory. An educated guess based on what you think you know, but can't be sure of.
Pretty much like the rest of life's decisions.
The other thing is the interesting interaction or counter-play at work. Having an activity that gets you up and keeps you going will keep body and mind active and healthy longer. Pulling the trigger to exit it might well hasten an ending. How soon is too soon or too late is unanswerable.
Pulling the trigger on an exit may become the safe play but unsafe play.
I guess part of that answer is in the question, what's next?
I got a taste of it when I tried early retirement at about 62, but didn't like it because I wasn't really prepared. I didn't really think through in advance what life would be like. Friends still worked, wife still worked, and once you have finally gotten around to those home projects that were put off for years, there wasn't enough to get mentally and physically active. I quickly hated it and went back to work, because I wanted to.
So I am now about to retire at 70, better prepared, and truly ready.
In very rounded numbers I spent the first 30 years of life really addicted to boating, mostly sailing. Then went cold turkey on the addiction for 40 years and didn't boat when life made that impractical. About 4 years ago the idea of returning to boating struck me hard, and the moment that idea struck me I was sure about it. It took time to develop the plan, time to figure out exactly what I wanted, and time to have the boat built and delivered. But now I have it, and I resent the time the residual job requires for a smooth exit. That just says its really time, this time.
I can say that just 4 years after the decision to go boating was made, my physical condition was different at 66 than 70. I picked a boat I thought best for a retiree's condition, and am glad I did.
One thing I notice as age begins to take its toll. I am not as agile as I once was, neither mentally nor physically. But judgement and wisdom improve. One stupidly simple example is, I get better at thinking through a project, being sure to bring the needed tools into the engine room, because climbing in and out to retrieve something gets harder. The net result is an improvement in efficiency.
Don't Let The Old Man In.
I am no particular fan of country music, but some of it does have a way of making a point. "I am not as good as I once was, but I am as good as I ever was, once." LOL.
Toby Keith wrote "Don't Let The Old Man In", inspired by watching his friend Clint Eastwood continue to be active in his life's work and play well past the age when most give it up and slow down. There is an interesting back story to the song, in this link.
Don't Let the Old Man In - Wikipedia
The thing is, Toby Keith passed away a month ago from cancer at 62. You can't know what it will be that gets you despite all resolutions on age and fitness.
Here are the lyrics:
Don't let the old man in
I want to live me some more
Can't leave it up to him
He's knocking on my door
And I knew all of my life
That someday it would end
Get up and go outside
Don't let the old man in
Many moons I have lived
My body's weathered and worn
Ask yourself how old you would be
If you didn't know the day you were born
Try to love on your wife
And stay close to your friends
Toast each sundown with wine
Don't let the old man in
Many moons I have lived
My body's weathered and worn
Ask yourself how old you would be
If you didn't know the day you were born
When he rides up on his horse
And you feel that cold bitter wind
Look out your window and smile
Don't let the old man in
Look out your window and smile
Don't let the old man in
And here is the song. Take it to heart.