I don't know if mentally comparing to your colleague's lack of work is conducive to being able to focus on your own role. I mean, sometimes it's those that aren't capable of doing more that get overlooked in times of promotions etc etc. You do more because you've displayed that you can. Granted organizations are only as strong as their weakest link, but without stronger links in there, the chain cannot sustain itself. I know it's an analogy but it gets me beyond the defeating comparison self talk. And it helps curb bitterness. It's on my mind, personally, as I've had a colleague not once but twice in several months assume that I cannot possibly be "happy" in my position. It's not about happiness for me and perhaps a bit of projection on her part but bitter isn't where I am at though I could be. I digress. I just picked up on the mindset.