Gratefulness.

Brother David Steindl-Rast on "A Good Day"...

You think this is just another day in your life. It's not just another day; it's the one day that is given to you today. It's given to you. It's a gift. It's the only gift that you have right now, and the only appropriate response is gratefulness. If you do nothing else but to cultivate that response to the great gift that this unique day is, if you learn to respond as if it were the first day of your life, and the very last day, then you will have spent this day very well ...