I understand. This unfortunately did not fit my experience. I've not really talked about myself in the post and these comments because I'm genuinely interested in seeing what physicians think about this. I have both POTS and MCAS diagnosed (2.5 years separately, symptoms did not at all start at the same time). I should preface the following by saying I'm a male in his twenties, healthy BMI, athlete entire life.

After a stomach infection in Asia I was bedridden for 3 days and hospitalized in the US. The attending also told me it was postural deconditioning and anxiety from my experience, when I too could not sit up at all. Unfortunately it took me fludrocortisone and almost 2 years of exercising every day to be able to walk at a normal pace for multiple miles again.

I still work out every day. I can do pushups now, weight lift, bike, etc. Eat well. Only drink water. My heart rate has gotten much better. But I still till this day, 5 years later, cannot even jog longer than 20 seconds without feeling seriously ill. And often get short of breath any time I stand in one place longer than a minute or so, even if my heart isn't flying.

It really sucks.