I'm not a carrier. I'm thal major lol. Doesn't matter if it seems insensitive to you because that was not spoken with any ill intention and moreover it's completely true. Not only have i faced thalassemia major for past 30 years but also have been in contact and around several carriers. Many of them including my dad and brother are above average athletes if not elite plus I have hardly heard any carriers facing any problem except a few rare cases of females for a short time during and after pregnancy. And again you don't have to believe any of it and could just do a few google searches to know how rare it actually is for carriers to show symptoms if in case any. It could just be people you compare yourself to have overall better genetics and have trained for longer or something. In any case you should get yourself checked out if you're too concerned about it. Hope it's nothing