“May you live all the days of your life.”—Unknown
When I was young, my reaction to this quote was something like “well, DUH. How would you not live all the days of your life? If you’re dead, you’re not living your life.”

Later (embarrassingly later) I had a different understanding, and I was really slow in getting it. The key is “what does the word ‘live’ mean?” I had originally interpreted it as the physical act of living, including breathing, cognition, awareness, things like that. Then I realized that it’s the existential definition of ‘live’. Implied by this is the pursuit of happiness, work, etc.
Today I realized that by ‘living’, the quote means ‘living well’, and could involve happiness, engagement, relationships, meaning, and achievement — the hallmarks of Martin Seligman’s PERMA model of flourishing. Living all the days of your life fully, which is what I believe the quote means.
I teach PERMA in my positive psychology class. Although I think the quote is a little trite, it seems like something I could introduce to my class at the beginning of the semester as a motto. That it sounds nonsensical at first, yet has a deeper meaning might be the most important attribute of the quote.