I have health issues so there is that. I think most 40 yo if they go to the gym on a good routine can have the energy. Add in a reasonable job (not an AI startup with a hammock in the kitchen). But 40 you are rolling the dice. 40+ you can die from things and it is not unheard of. It is quite old in a way. You can also have issues unexpectedly that depleat capacity.

Just reread your comment. Don't kill yourself!!! Help raise your niece or nephew or friends kids. You can pass on social inheritence! And you can work in a cube at Google and send half the money to kids charities.