You sound hesitant and not confident of your own ability.

Personally, the first thing I'd do is remove myself from people like that. What a painful way to live - there are a hundred other different environments.

If you feel like you need to be there, you probably have already realized it - they are full of shit - that is sales. Most sales people are confidence tricksters, they spin bullshit. You have a potent weapon, a brain. Use it, whip them down. They're generally morons, with confidence.

But, I would say get out of the environment.