One thing I've really had to get over is "illusory inferiority" - I am objectively an extremely good programmer, as demonstrated by my accomplishments and career path, but I constantly underestimate the value I provide to my employer because the contributions I make don't always feel important.

As an analogy, I can imagine a slightly bored senior sushi chef who is a master at preparing fugu (poisonous blowfish). The value they provide is huge, but they've done it for so long that it does not provide a challenge.