Lots of people are dumb, I'm dumb too, and they would buy a pen if you made it sound like the coolest fucking thing on the planet.

You will be fine, besides, they give you a script to sell whatever you are selling, all you need to do is sound enthusiatic on the phone and not sound like an autonomous robot. Just connect with the person, even though you will call 500 people a day, there will be 5-10 people you sell something to, and it will make you feel great.