You can do this through statistics or survey results from your existing customers. Imagine the conversion capability of a statement like, “Seventy percent of customers using our product shaved 10 points off their golf game within a month!” You can just hear them clicking your CTA. Just be sure not to make any outrageous claims—especially income claims. You want to preserve their sense of trust in you.
For the example above, this might sound like, “If you’re tired of people asking to pass you on the golf course, this product is for you. Imagine how it will feel when you start winning games, and accepting business golf match invitations, because you’re confident in your newfound golf game. This program can help you make steady improvement that you’ll begin seeing within a couple of rounds.”