I am guessing you mean A Good Day: A Gift of Gratitude by David Steindl-Rast and Louie Schwartzberg (as opposed to the children's book A Good Day by Kevin Henkes). If I am mistaken, please feel free to repost the question. As it stands, A Gift of Gratitude is touching, for sure, but not really a novel. It is a quest for gratitude in the midst of nature filled with spirituality.
Supposedly, Brother David Steindl-Rast, a Benedictine Monk in the Roman Catholic Church was inspired by a tiny film called Gratitude. Thus begins this monk's legacy! The book pairs messages about gratitude with the beautiful, natural photos of Schwartzberg in a collection of platitudes that makes a GREAT gift for anyone! As such, though, it's really hard to give a summary except to say this book suggests that we be thankful EACH DAY for all of God's great gifts. Perhaps the best way to summarize would be to take a few quotes from the collection here and explain them. Here are two that are particularly poignant:
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 the only gift that you have right now. And the only appropriate response is gratefulness.
I have never seen it put quite this way before, that this very particular day has been given as a gift to you, a particular person, for a particular purpose. To waste the day is to waste the gift. Time, in itself, is a gift within this day. Gratefulness to God id "the only appropriate response."
Everything is a gift. The degree to which we are awake to this truth is a measure of our gratefulness, and gratefulness is a measure of our aliveness.
Later in the book, Brother David Steindl-Rast goes even further and extends gifts not just to this day, but to EVERYTHING. This is a "truth" that he mentions here. If we don't understand that truth, we are not "awake" and are unable to be grateful and are not, then, truly alive.