Here's what you do. When the children leave home, Sell the big city house and downsize to a country cottage near a preserved railway. In UK you might be able to bank half to one million, or more on which you can comfortably live provided you avoid Ferraris and High Society.
Now volunteer on a preserved railway, for little or no pay. You will acquire a whole new social life, of like minded, efficient, friendly, and intelligent people, who have really satisfying work.
And that's how it's done. High powered and overworked executives go back to being simple machinists -- often they survive for years.
Bob Gartside