I constantly learn and grow.

Learning after thirty works differently, and people mistake the difference for decline. It goes in more slowly and it attaches to more things once it's there.

A ten-year-old picks up a language by absorption. You pick one up by tying it to everything else you already know, which is laborious and is also the reason yours ends up load-bearing rather than decorative.

The reliable test is whether you can explain it to someone without notes. If you can, it's yours. If you can only recognise it when you see it, it's still a visitor.