When you're selling anything you should assume people think you're lying. We both know you're this wonderful, charming individual who wouldn't sell anything to them unless it would benefit their lives... but how are they supposed to know that?
That's why customer testimonials and other proof elements are so important in marketing.
Increase your believability
When marketing your business you have to work really hard to increase your believability. Because without trust you're never going to sell anything. Building trust with your prospects is one of the hardest but most influential things you can do.
Because when people trust you they're much more willing to buy from you. Why do you think I spend over an hour a day writing articles and blog posts? Because I know if I share great information with you I'll eventually gain your trust and that could lead to us doing business.
And of course because I enjoy it... there are much more lazier approaches I could take to building trust. But they're probably not as effective in the long run.
Why should people believe you?
I constantly see businesses talk about their great service. But nearly every business does that... so why should I believe them? If you want to claim something you need to back it up with proof.
For example if you're voted the number one in your industry for customer service... then you obviously should be promoting this fact as you have proof to back it up.
Creating proof
Of course you don't have to wait around for someone else to hold an awards ceremony either. You could survey your own clients for customer service (which you should do anyway) and then use the results in your marketing. E.g. "95% of our clients rated our customer service good to great."
And there are many other types of proof that you can use. The key is you think about what you're saying in your marketing and then back it up. Because without proof you might as well not say anything.
Using customer testimonials
No business has any excuse for not using testimonials from satisfied clients. They're easy to obtain (just ask) and the voice of your clients are a thousand times more believable than your own. It still astonishes me how many businesses don't use testimonials in their marketing.
What you do next
Think about what proof you can use to support your marketing and then put it to use. Ensure you have customer testimonials and other proof elements in everything you do. Remember the more proof you have... the more you sell.

Thanks for the reminder!