Freaking out on client requests

I am trying to develop my business and not happy where I am right now with the number of clients.

However, by doing some awareness work, I realize I am scared (freaked out actually) to receive a new client request. My first thoughts are “OMG, how am I going to handle this, I don’t have a solution to their problem, I’m not sure I’ll be able to deliver, so much pressure is on, etc.”

I can guess that those kind of thoughts are not super helpful in developing my business. I need to believe in my abilities/ capacities to handle the problems clients are bringing to me.

Any thoughts on how I can achieve that?