Powerful stuff, source unknown:

I had a very special teacher in high school many years ago whose
husband unexpectedly died suddenly of a heart attack. About a week
after his death, she shared some of her insight with a classroom of
students. As the late afternoon sunlight came streaming in through the
classroom windows and the class was nearly over, she moved a few things
aside on the edge of her desk and sat down there.

With a gentle look of reflection on her face, she paused and said,
"Before class is over, I would like to share with all of you a thought
that is unrelated to class, but which I feel is very important.  Each
of us is put here on earth to learn, share, love, appreciate and give
of ourselves. None of us knows when this fantastic experience will end.

It can be taken away at any moment. Perhaps this is God's way of
telling us that we must make the most out of every single day."

Her eyes beginning to water.  She went on. "So I would like you all to
make me a promise. From now on, on your way to school, or on your way
home, find something beautiful to notice.   It doesn't have to be
something you see - it could be a scent-perhaps of freshly baked bread
wafting out of someone's house, or it could be the sound of the breeze
slightly rustling the leaves in the trees, or the way the morning light
catches one autumn leaf as it falls gently to the ground.

Please look for these things, and cherish them.  For, although it may
sound trite to some, these things are the "stuff" of life. The little
things we are put here on earth to enjoy. The things we often take for
granted. We must make it important to notice them, for at any time...
it can all be taken away."

The class was completely quiet. We all picked up our books and filed
out of the room silently. That afternoon, I noticed more things on my
way home from school than I had that whole semester.  Every once in a
while, I think of that teacher and remember what an impression she made
on all of us, and I try to appreciate all of those things that
sometimes we all overlook.

Take notice of something special you see on your lunch hour today. Go
barefoot. Or walk on the beach at sunset. Stop off on the way home
tonight to get a double-dip ice cream cone. For as we get older, it is
not the things we did that we often regret, but the things we DIDN'T do.