self doubt and not feeling in control

Hi. I recently set a goal to make my first $100K in one of my launches. The goal feels scary, but in some way do-able. But then when I actually worked out that I have to sell 400+ of my product to meet that goal, I felt a little sick and the self doubt rolled in. One of the thoughts that keeps coming up is this intense fear that I can do all that I can to market it, but in the end “I have no control over how many people will actually buy”.

This makes me feel anxious and demotivated. Which in turn makes me show up in a less motivated way etc.
I want to change this, but I just keep thinking that the thought is true because I DON’T have any control over other’s actions (e.g. them buying).

It feels like I cant do anything to insure my success and make sure I hit my goal. How do I change or approach this thought in a way that would serve me?