I eat Brian Tracy books up like it's a big piece of pie. Brian Tracy books provide me with that extra boost of motivation that I find myself needing on my down days.
In this book he talks about the importance of confidence and self-esteem and how these two factors separate the successful salesperson from the unsuccessful one.
Sales is an essential part to any business and a necessary skill to have under our belts as entrepreneurs! (This is a good book in general for confidence building as well!)