I experienced this in my early 30s. I really thought my career was over, I felt I was making such poor progress in various tasks and learning what I needed to f

I experienced this in my early 30s. I really thought my career was over, I felt I was making such poor progress in various tasks and learning what I needed to finish a fairly large project. In retrospect I actually knocked that project out of the park, but I was miserable for a number of reasons, burned out, and siloed off on a project that the company was bizarrely apathetic about. I developed a bleak outlook on what I was doing, and as I hit obstacles I think the bleak outlook increasingly extended to myself. It was a great learning experience. These days I'm fairly sure I'll continue to learn because I love what I do, so long as my brain's still working at least. I might slow down here and there, but it's a mistake to think you've actually hit a hard limit or something. It's almost certainly external. When I feel down or like I can't do my job well enough, I just remind myself how far I've come despite how low I've felt before, and how things have continued to go well. Don't let yourself get overwhelmed. Do let yourself take a break, though. You might need one to get a fresh perspective on things. Good luck!