How Long Do You Have To Be Proving Yourself?

I've previously mentioned Austin's Kleon's quote (which is on its own a conclusion brought out by Ann Packer's words): "Let go of the thing that you’re trying to be (the noun), and focus on the actual work you need to be doing (the verb)". Just do the art and forget about being an artist. But does that work? In general: absolutely so. If you draw, you're an artist. If you run, you're a runner. The issue comes the other way around, when you focus on the noun (which is exactly what Kleon highlights): what if you don't run enough? Can you call yourself a runner? Who cares, you're running. This is the best part, because you really don't have to prove the noun applies to you. I'm doing the verb. Shush. But what if I've been calling myself a runner for years? Let's say it's something that I've enjoyed a lot, have done on and off (I'm no professional after all), but now my legs can't be pushed to the same limits as back then, and I can't run anymore. Have I stopped being a runner?…