On the hours that were never short
“It is not that we have a short time to live, but that we waste much of it.”
The complaint is always the same: there isn't enough time. Seneca's answer is unsentimental — there is plenty, and we spend it the way a rich heir spends money, on nothing we could name afterwards.
What he means by waste is not rest. Rest is a use. Waste is the hour given to something you did not choose and would not choose again, handed over out of habit rather than intent.