Love
"What if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and every sigh and everything unutterably small or great in your life will have to return to you, all in the same sequence and order - even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned over again and again, and you with it, you grain of dust!'"
I would do it again, and innumerable times more to return here eternally.