To proselytize (PRAH-suh-lih-tize) – from the Greek for “convert” – is to try to persuade someone to change their religious or political beliefs or way of life to your own. As I used it today: “If you can add to the promise of showing [your prospect] the person or thing that is responsible for his weight… then you have not just a potential customer [for your diet product], but a potential proselytizer for your brand.”