I don't know what it means to believe in yourself...

Believe in yourself.

I don't know that I've ever known what this means. I've certainly heard it a lot. Any kind of self-help guru is going to advocate this message. I love it when people say, "you just need to believe in yourself," as if that somehow resolves every self-esteem issue out there. I imagine a conversation going something like this:
Me: "I have low self-esteem."
Other: "You just need to believe in yourself."
Me: "Oh. Is that all I need to do? Ok. I guess that was the answer I've been waiting for all my life. Gee, why didn't I think of that?"

To everyone in the world: "Don't you think if I knew how to believe in myself, I would have done it by now?!?"

 The thing is - I agree. People SHOULD believe in themselves, because it sounds fantastic. But what does it mean?

To me, "believing in yourself" actually has negative connotations. For me it evokes feelings of pride and self-centerdness. Anything that requires "believing in myself" means putting myself first. I'm sure I'm wrong about this, but I feel like my religion teaches that you should put God and others first, and that you come last. The debate I'm currently having with myself is this: The first great commandment is to love God. The second is like it, love others as yourself. (Matt 22:37-39) My question is this: if you don't love yourself, are you keeping that commandment? The phrase "as yourself" is what's confusing to me. How can you love others as yourself if you don't love yourself? But if you love yourself, doesn't that mean you're putting yourself first?

I don't know. Maybe I'm just overthinking it.

Is there anyone out there who teaches a class on how to believe in yourself, or something?

p.s. I HAVE googled it and I haven't come across any satisfactory answers thus far...