Actually, I'm not sure there is reason to be sorry about being not too self-assured. Granted, the self-doubts should not be so bad that they're paralyzing. But I think it's healthy to recognize that not everything we accomplish can be attributed to skills.
I remember one woman who might have died without me. At least to my knowledge she survived and I played an important role in getting her to the right hospital in time. I was an emergency doctor, then. The German medical system has doctors working side by side with the paramedics at the scene.
When my paramedic driver and I arrived at the scene, the other paramedics were just measuring the woman's bloodpressure. She had a faint pulse on her left arm and a low blood pressure. I felt her pulse on her free arm, where her pulse was strong. And her blood pressure there was normal.
That was the important clue to the right diagnosis. She was suffering from a rare disease, which most doctors encounter maybe once in their lifetime. If we hadn't arrived at precisely the moment we did, if I hadn't chosen her right arm to feel for her pulse, I would have thought she was suffering from a heart attack. We would have taken her to a closer hospital without the cardiac surgeons she would have needed.
It took medical skills to help her, but there was also quite an amount of good fortune involved.
I think that people who don't believe that they're the best, most accomplished guys to ever set foot on the face of earth might end up doing there job a little better, because they're humble enough to recognize their limits.