You might not realize this, but you're bad at a lot of things. You're genuinely not good. Seriously. That's true for most things. Like, more than 90% of all things. That's the case for you, me, and everyone else. I don't know how to tune an engine or write a decent poem. I also don't really know how to consistently write articles for a website. The good news is, you're capable of getting better. Better at everything.
When you find yourself performing poorly, it's going to feel uncomfortable. Maybe you're at the gym surrounded by people that are stronger or faster than you. Maybe you're in the office and are surrounded by "real professionals" and you don't feel like you fit in. Maybe you feel behind in class. Maybe you're literally trying to hit a target (golf, darts, archery, etc...) and you consistently miss. All of that can feel, and very likely will feel, uncomfortable or frustrating. But, once you understand that feeling to be the start of a journey, a journey of realization, improvement, and pride; you can teach yourself to become comfortable with it.
You have to be willing to try something you suck at. Otherwise, you'll never try anything new. Ever.
I haven't lived a lot of life, but I know that's no way to go about it. There are too many things out there worth experiencing. For a lot of those things, the learning curve can be sharp and unforgiving, but hitting the straight away exposes you to new types of enjoyment that were previously hidden behind locked doors.
When you feel uncomfortable, you should feel excited. This is a chance to get better! This is a memory to look back on in 6-12 months and laugh at your own inadequacy. It's like looking back on a previous version of yourself, one that's almost unrecognizable. How foolish were you when you were 12 years old? What about 14? 16? 21? You are constantly improving. Starting something new and feeling the discomfort associated with it is the first step!
If you're lucky, you'll experience discomfort throughout the journey. From beginner to novice to intermediate to advanced to mastery. This is why you have to become comfortable with discomfort. The more you embrace the discomfort the faster you move up the ladder. Otherwise, you'll get stuck.
Taking a step forward into the unknown helps keep life meaningful. So go out there and try whatever it is you've been too scared or uncomfortable to try. Start exercising. Try a new hobby. Start that passion project you've been dreaming about. Try writing, singing, running, whatever. In all likelihood, it's going to be a little rough, uncomfortable, and you're going to mess up. From there, you keep going until someday you look back and laugh, rejoice, and take another step.