That most people spend their entire lives not knowing how or why to live and end up doing a lot of really silly things trying to emulate other people who are supposedly mature. This isn't limited to adults either. Children do it at pretty much all ages, try to behave "like a such and such year old". And I have found being and trying to be what is considered mature to be kind of unfulfilling. I rather enjoy being childish more. I don't give up on joys because they are "for kids". And I am never short for joys.