Here are a few more gems from Seneca:
"As it is with a play, so it is with life: what matters is not how long the acting lasts, but how good it is." (Letter LXXVII)
"For a life spent viewing all the variety, the majesty, the sublimity in things around us can never succumb to ennui--the feeling that one is tired of being, of existing, is usually the result of an idle and inactive leisure." (Letter LXXVIII)
"In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes." (Posidonius, qtd. in Letter LXXVIII)