People are generally pretty verbal when it comes to giving negative feedback. If another person does something that bothers you, and you don’t say anything, he or she is likely to continue that behavior. So you speak up.
On the other hand, positive thoughts and feelings often go unsaid. I think this is very unfortunate.
I believe that if you think someone is a great person, you should tell them. All that we have in this world is this moment right now. If something tragic were to happen, the other person would never find out that he or she made such a profound difference in your life.
This is why I made a commitment to always tell people when they do something that inspires me and touches my heart. It is the least I can do to repay them for all their kindness.