From Vala Afshar
The first 20 years you measure success with grades, only to realize that the real value is in learning to learn, un-learn and re-learn.
The second 20 years you measure success by how much money you made, only to realize that how you spend time, and with whom, is most important.
From Captain Jean-Luc Picard (The Inner Light):
"Seize the time...Live now. Make now always the most precious time. Now will never come again."