Once someone has made a positive or negative judgement about a potential job candidate, that judgement colors subsequent performance appraisals. What this means is job performance matters less for your evaluation than your supervisor's commitment to and relationship with you.
Many studies have documented the influence of numerous factors, ranging from educational credentials to race and gender, on careers, with performance often having a statistically significant but substantially smaller effect on advancement.
Emotions and behaviors become self-reinforcing: if you smile and then others smile, you are more likely to feel happy and smile. This reflexive quality in human interaction means that a mood or feeling, once generated, is likely to be quite stable. Grove might have to act confident and knowledgeable at first, but as others caught that feeling, it would be reflected back, making Grove himself more confident.
Part of it is self-discipline and part of it is deception. Deception in the sense that you pump yourself up and put a better face on things than you start off feeling. But after a while, if you act confident, you become more confident. So the deception becomes a reality.
Churchill: "Words are the only thing that last forever". Language that influences can create powerful images and emotions that overwhelm reason.
Don't hide in the legal technicalities. Confront common sense understanding of what's right and wrong.
If you make people laugh, you can tell them anything.
It is better to widely disperse your network building efforts and build many weak ties. Don't get hung up on making a favorable impression in any single place, but instead find an environment in which you can build a great reputation and keep trying different environment until this effort is successful.
Many people want to demonstrate how wonderful they are by working diligently to change others' mind and repair their image. But such efforts are seldom successful.