Jesus healed ten lepers and only of them came back to thank him. It is important not only to be grateful in our hearts, but to take action on that gratitude by saying "thank you" or passing on our blessings to others so that they also might be blessed.
Based on Luke 17:11-19
On the way to Jerusalem Jesus was going through the region between Samaria and Galilee. As he entered a village, ten lepers approached him. Keeping their distance, they called out, saying, ‘Jesus, Master, have mercy on us!’ When he saw them, he said to them, ‘Go and show yourselves to the priests.’ And as they went, they were made clean. Then one of them, when he saw that he was healed, turned back, praising God with a loud voice. He prostrated himself at Jesus’ feet and thanked him. And he was a Samaritan. Then Jesus asked, ‘Were not ten made clean? But the other nine, where are they? Was none of them found to return and give praise to God except this foreigner?’ Then he said to him, ‘Get up and go on your way; your faith has made you well.’
(New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org)