I think that athleticism can best be considered in a relativistic manner and that we are all our own best opponents. I think the Women's Running article is great for showing someone who's not the 110 lb 19 minute 5K types they usually show out there, cruising along, with good form, looks just as powerful as the thinner person. Maybe even more so as, if you look at her as a member of a demographic cohort, she is probably in the top 5% performancewise whereas the usual runners are simply models cruising around Central Park on a photoshoot.
When I'm out running, I see a lot of diversity on the trails. I try to thumbs' up, salute, shaka, whatever all the folks and certainly acknowledge anyone older/ bigger/ etc. I don't need to tell them my whole saga but I can salute their efforts. I did this to an older lady out with a walker, I dunno, maybe she'd had her hip replaced or something and the thumbs' up made her laugh.