This would actually really bother me, in part because my therapist is an athlete and the fact that staying physically fit comes much more naturally to him than to me has been difficult for me at times.
I feel like if he was just casually walking on a treadmill--or worse, jogging/running--during our session, it would just sort of rub that in. Like, "Oh, look how physically fit I am--I can jog and still carry on this conversation." I'm sure he wouldn't mean it that way, but I think that would be going through my head.
Now, if we were to go for a walk *together*, that would be different. I've walked briefly with ex-MC and ex-T a couple times in the courtyard of their office when I was having a panic attack. I feel like the walking and being outside helped me to calm down. I doubt Dr. T would ever be willing to do that though--then again, we met outside of a coffee shop a few times during the pandemic, so maybe? Or if he were to demonstrate some stretching moves in the office, which I think he did once before (like ways to calm myself and meditate).
I suppose the difference for me is if it was more something we were doing together, rather than him trying to fit a workout in while meeting with me. I suppose if that was the only way we could meet, then possibly?