There are a few metrics other people have considered that he seems to have overlooked; daylights, sunsets, midnights, and cups of coffee are all highly quantitative. Qualitative measures are probably to be preferred though, e.g. Love.
You left out the most quantitative measure of all: 525,600 minutes.
Whenever I whine on my b'day about turning-a-certain-age, there's always some older person in the room who gets all wistful and says, "Ah, to be N again..."
Oh thanks! Way to mellow my harsh man!
(I gotta stop inviting that guy.)