One little secret, for young scientists who haven’t discovered it yet: the most accomplished scientists are not necessarily the brightest people in the field. Creativity and dogged determination are important, but two qualities also distinguish great researchers — courage, and the ability to claim ownership of one’s domain of expertise.
The courage to fail, and the acknowledgment that public failure is a possibility, is critical for a highly successful career. You need to be willing to promote your theories, even though they may be wrong or may be misunderstood. As an extreme version of this, see Richard Feynman’s wonderfully titled book: What Do You Care What Other People Think?: Further Adventures of a Curious Character. Before you stick your neck out at a conference or in a publication, you need to get informal feedback from colleagues. Once you feel confident about your work, however, you need to take the risk that you may make a fool of yourself — even if you are right.
In order to gain this confidence, and to have earned it, you must be able to claim some turf in your scientific territory. Care enough about what you have observed and understand its scientific value well enough that you can claim it as your own. There’s a tricky balance here: you must feel so confident of your work that you can defend it, yet you must be flexible enough to yield if you are proven wrong with good reason. Too many well-known scientists have repeated their disproven theories at conferences long after their closest colleagues have quietly written them off.
Are you a genius whose work nobody understands, or are you a stubborn, intractable person who won’t admit that you are wrong? Your closest associates can help here, if you let them. Listen to their logic, trusting that at least they don’t intend to shipwreck your career for the sake of their own success.
Once you can properly own your accomplishments, courage will come more easily. Junior scientists should look to their seniors for examples and inspiration. Find people who have persevered despite repeated rejections and eventually remade their fields. And don’t be afraid to be afraid. The only way to build your courage is to acknowledge and then ignore the fear.