Your most productive age if you live too short or too long.

right now writing my books is my most productive age

I am not sure what you mean, perhaps you mean live too long and run out of money or are not productive? I am eighty one and am handicapped so I am not productive in the sense of earning money in a job but I share an apt with my son and I do most all the housework and I make a small amount of money to add to my social security check each month. I think in some ways the last few years were my most productive but I have earned my retirement now. I hope my son does not think that I have lived too long.