I don't have it that bad, but the graph in that article certainly resonates with me. I don't feel like an impostor, exactly, but I do tend to feel like "I'm nothing special, everyone knows/can do that".
Looking at that graph helps a lot, because it reminds me that no, not everyone has the knowledge/experience to be a good translator, to take myself as an example. It also helps to make a list of the component parts of what you do. For example, as a software translator, I have a near-native command of English, an excellent command of my own language, experience with all kinds of tools, knowledge of how to get the most out of the (often lacking) context, I've done a little programming and work with HTML; very little, but it really helps me determine what parts of a syntax example are translatable.... I could probably add more items with a little thought.
Another thing that helps is comparing myself with others. They always say you shouldn't do that, but lately I have been editing the work of other translators, and when I see the mistakes they make sometimes, I can't help feeling that I mustn't be that bad after all.
Another thing I've just recently read about and haven't had occasion to act on yet, is to save any positive feedback you get. Save any letters, e-mails etc. where someone compliments you. Those can also help in your next performance review. Maybe write down oral compliments somewhere, too.
And remember the saying: "Everyone is ignorant, only in different subjects".
Your job, should you choose to accept it, is to comment on this thread explaining the most awesome thing you've done this month. You may be as blatantly proud of yourself as you feel. You may unabashedly consider yourself the coolest freaking person ever because of that awesome thing you're dying to tell everyone about. This is the place to do just that.
Remember, however, that this isn't any kind of progress thread. Nor is it any kind of proposal thread. This thread is solely for people to talk about the awesome things they have done. Not "will do". Not "are working on". Have already done. This is to cultivate an environment of object level productivity rather than meta-productivity methods.
So, what's the coolest thing you've done this month?
(Previous Bragging Thread)