Learning to appreciate your bright side is incredibly important to high performance. Bright-side personality is your normal personality on an average day, or when you are seeking to make a good impression.
It's important because ultimately we only really shine if we can match our bright-side, normal behaviour with a role, task or environment that values our natural or normal behaviour. So if Sally is normally talkative, extroverted, engaging and enjoys meeting new people and she exhibits those behaviours naturally in the course of her day, sales is an area that values those abilities. Selling will be much easier for Sally than for John, who is a withdrawn introvert and doesn't really enjoy meeting new people. When something comes naturally to someone they are almost always better at it; if Sally was asked to stay in the office and write up a detailed report she would struggle, but John would be in his element.
Anyone can do anything once or twice; most people can be encouraged or cajoled into behaving in a certain way or doing certain things now and again. Sally could write the detailed report and John could maybe make a few sales, but if it doesn't come naturally then performance will be patchy and inconsistent. High performance is about consistency.
Everyone in the right situation can sell but only the people who have a natural bright-side affinity to selling are ever really good at it. High performance is much more likely when what ...