Difficulties in thank you

There are a few things I find difficult in thanking people.

The words thank you itself - does it suffice? Do you have to have it on a piece of paper? Carved in stone? Etched on a monument? How do you show that you really are truly grateful for a deed, for kind/encouraging/thoughtful words, for gifts, for love and compassion?

While I thank the people who really were there through the experiences and the memories made over the years, it's the people that help me realize my potential who made all the difference. And to all of you who thanked and continue to thank me, I am forever grateful as I live off of your gratitude.