Self-esteem

Why should I have self-esteem? Should the things I do (or don't do) have any bearing on my self-esteem? What about my professional accomplishments? What about how other people feel about me?

The way I see it, nobody is perfect, and using any of the above criteria for developing self-esteem seems to bump up against this fundamental limitation. In each case, I would develop a standard for good behavior and bad behavior, good achievements, and the failure to achieve. The good behaviors and achievements would supposedly give me self-esteem. But the converse is always that the bad behaviors and the failures would lead to low self-esteem. In the cases where I don't live up to my standards, I would need to have compassion for myself, which really just means lowering my standards, until there are none. Is this what it means to allow myself to be imperfect?

Does allowing myself to be imperfect mean that I no longer have to try to be perfect? I no longer have to strive to be better than I am because striving to be perfect is doomed to fail? How can I not punish myself for failing, while still trying not to fail?

It must be enough that I try to be better every day, even if I fail some or most or all of the time. How exhausting! But how else could it be?

And if one day I forget to try, or am too tired or angry or sad or happy to try to be better? Should that give me lower self-esteem? Or if I stop trying altogether, or if I go completely in the reverse direction and begin to do things that are morally reprehensible, should I have low self-esteem? If I harm someone, or even kill someone, should I have low self-esteem?

Religion offers some neat principles to answer all of these questions, but from pure intuition or logic or reasoning, I don't really see where self-esteem should come from, or whether it needs to have any basis at all.

From a Catholic perspective (because that is all I know) self-esteem should exist simply because we are children of God. That is, by the simple act of being a human and being alive, I deserve to have self-esteem. My worth derives from God. We should also strive to please God, and to be more like him at all times. When we inevitably fail at this pursuit, there is a nifty way to address the guilt and recrimination that result: by confessing and doing penance and trying again. 

This is all very messy and confusing. I'm typing at the speed of thought, but this question plagues me and I would like to revisit it in the future.