Eternal return is a concept which posits that the universe has been recurring, and will continue to recur in a self-similar form an infinite number of times.[Wikipedia]
On my green T-Shirt are the words
"All this has happened before, and all this will happen again."
It's not that the struggles we endure are made less by this thought; but it is comforting to understand that although these issues are personal to us in so many ways, we are not unique in our efforts: someone has been where you are now; tomorrow, another person will take your place.
There are so many ways to get to the same end solution. Hated or loved, selfish or altruistic; maybe we'll get it right the next time, if we don't manage get it right this time around.
What ever choices we make doesn't guarantee we wont get a bruise or two through the experience 'tho.