I'd rather be a could-be if I cannot be an are; because a could-be is a maybe who is reaching for a star. I'd rather be a has-been than a might-have-been, by far; for a might have-been has never been, but a has was once an are.
-- Milton Berle
Mistakes show us what we need to learn.
-- Peter McWilliams
When we are no longer able to change a situation, we are challenged to change ourselves.
-- Viktor Frankl
Regret for the things we did can be tempered by time; it is regret for the things we did not do that is inconsolable.