It's not a lie if you believe it.
Seriously, age is not a big deal, when selling.
My Father owned a sporting goods store on the Jersey Shore and I worked there from the age of 10 until I was 16 and I remember one time someone was looking at a product line he sold.
My Father said, "Go sell them.", I was 12 at the time.
The guy who was looking asked me how old I was and I told him I was 12 and he said that I was just a kid and didn't think I knew the products.
I then rattled off the differences between 9 different products in that product line, why he should buy from us, and that we can have that packaged for him in 10 minutes, and he ended up buying one of the better ones.
Know your product or service better than anyone else, be able to explain it better than anyone else, and age won't be a factor.