I agree with PloddingOn.
I consider myself a runner but am nowhere near a 9-minute mile at the present time . Goodness me, I go out in any weather (even 'bum-numbing' levels of cold
) and get hideously frustrated when either I'm not able to go out running or I fall short of targets I set myself (something which has happened rather a lot in recent times). Not sure whether 'athleticism' comes into it for me, but certainly purpose.
Not sure whether I call myself a swimmer or not. I deliberately don't go in the lanes cos I don't consider myself good enough, but I do duck my head under the water properly when doing breaststroke, and at least attempt to swim other strokes! An infrequent swimmer perhaps as well, but I do try to take it seriously when I'm there.