"You can choose to live a long life or a happy life" I don't remember who said this, but it was in regards to not having fun because you're too concerned with health/consequences/etc. It's about enjoying your life and not always having to be responsible (there is a time for fun). After all, what's more important- happiness, or longevity? That's up to you, but happiness far outweighs the idea of living a miserable boring and long life until I'm like 100.
"If you're going to kick authority in the teeth you might as well use two feet" This is actually a quote from Keith Richards, but it's something I believe is very potent not just in terms of rebellion as is literally suggested but also just anything- if you're going to do something, do it properly, not some half-hearted job.