It is impossible to overestimate the ability of a person to thank and be grateful. I'm not talking from the position of the tons of literature I read on the subject, and from the bell tower of my own experience. Gratitude makes it clear that you need and that you need others. Gratitude eliminates selfishness and disposes people to us. Gratitude has a positive effect on health. Thank nothing not worth. In this case, shyness and modesty should be safely sent far away and not to be silent, if it would be more appropriate to say "thank you". So you're right @paolajane, to be grateful, is the only way to appreciate life and everything it has to offer. There is no other way to appreciate.