It sounds counterintuitive, but not having a job makes you realize how little time you really have. Somehow when you're busy working and hustling here & there, you don't notice the fact that so much life is slipping away. ("Life is what happens to you while you're busy making other plans" - John Lennon) Things you've always wanted to do, or really enjoy but haven't "found the time for" are put off week after week, month after month, year after year. However, when you're on sabbatical, you no longer have the "I don't have time" or "I've been busy with work" excuse - because you DO have every hour of the day at your disposal. I learned that, even by doubling (or more) my leisure time by not working, I still don't have enough time to do everything I would like to do in my brief existence on this planet. For me this drives home the fact that life is about setting priorities. If you haven't done something lately like visit your parents, learn French, call an old friend, or spend a long weekend away it isn't because you "haven't had the time", but that you've chosen not to do it and have instead put something else in a place of higher priority.

I believe taking responsibility for these choices ultimately adds fulfillment to one's life. My most valuable possession is time, and for me happiness is spending that time as I choose: time to follow my passions, time to spend with my wife & family, time for friends, time to give back to my community. A sabbatical helps to quantify the value of this precious time.