The song mixes two ideas about life (several philosophies like existentialism and stoicism share them):
1. Not only does life not last forever, but it has no ulterior meaning or motive. We live and we die for no specific objective, so we might as well enjoy the show, share our secrets, rise to our personal best and follow our interests. Once you accept yourself maybe there are no more mountains left to climb.
2. It is useless to worry about what lies outside our circle of control. We should accept the things we cannot change, smile, and enjoy the view.