Impostor syndrome is when you experience the sentiment of not being enough, even though you might be performing well. In the long run, having the persistent fear of being exposed as a fraud can negatively impact how we perform.
In strategy consulting, the impostor syndrome can be strong, as you are around C-levels and VPs that have more experience than you and have an impressive depth of knowledge in their field.
Couple weeks ago, a young analyst told me that he did not know how to manage his feelings of impostor syndrome. While I'm constantly dealing with self-doubt (and I think it's healthy), I manage it by expecting that I will not have most of the answers, but I can ask questions. In his blog Questions or Answers, Seth Godin says that we can add value in two ways: "You can know the answers. You can offer the questions. Relentlessly asking the right questions is a long term career, mostly because no one ever knows the right answer on a regular basis."
Asking the questions is the easy part, as you could simply ask the famous 5 Whys. The problem with the 5 Whys is that they don't build the requirements for a good answer: some mutual understanding and trust. So how do we ask a good question? In his book, Why Are We Yelling?: The Art of Productive Disagreement, Buster Benson describes what makes a good question: "To ask a good question, walk right up to the perimeter of your current understanding about something and find a question that you don’t know the answer to. Great questions create space for surprising answers to fill them. If we ask questions that can only yield answers that we already expect, we’ll never be surprised and we’ll never find a new wandering path through the world. But if we ask open-ended questions that have no predetermined answers, we can take steps farther and farther away from where we started."
A good question will be open-ended (not yes/no) and will try to understand the other person, rather than validate our own perspective. That way, it is possible to have an open and honest dialogue where the person feel like they're given the opportunity to share their true thoughts. I've found that by doing that, we're able to get on common ground and tame impostor syndrome for a bit.