I saw a post by Dov earlier that derided the concept of self-esteem. I find this concept brought up often, and I find it interesting because there is no good definition for it. There is such a thing as
low self-esteem, but it's odd calling something "low X," where X cannot be be defined unambiguously. I think the question of just what this is (if anything) is considered sort of the frontier in psychology. Since it's not measurable (whereas behaviors are) I am pretty sure they will never get anywhere with this.
I find that when I am davening I am about as happy as it gets. I don't have joy when I daven, but I finally feel like I am doing what I am supposed to be doing. "I create this existence for my glory."
I heard a vort which I think is from Rav Yacov Kamenetsky zt"l. It's about animal rights. I think he said that we cannot know how a donkey feels when it's fully loaded. It's a beast of burden, and it only really fulfills its true potential when it carries tremendous loads. Its whole skeleton is probably designed for that.
It's like a marathon runner. A person who is out of shape when he runs too much he is very unhappy, but a pro, when he is in the middle of it his heart is pounding, and he feels great.
So sometimes I think that true self esteem must be attained when you worship Hashem and you have no desire for anything else because from previous experience you know you are not really cut out for anything else.
I have no proof obviously