I don't discuss things with them unless asked and then I say things like, " he loves books" or "he does things on his own timeframe" and then smile and move on. Comments that are specific get a smile with "he loves to practice" or something related to effort or hard work or internal drive. My kid seems to have super hearing and I have to assume he hears everything. Comments made as a joke in passing about him pushing me to do things really hurt his feelings once and I have promised myself to never do it again. I treat athletic abilities no differently.
I don't want him to brag or be showy in any area, but I do want him to feel proud and know we are proud of who he is. When I have successes in my life, I don't brag to strangers or coworkers either.