Why do I feel less symptoms when relaxed?

Can someone explain the logic behing this? I was the first one to criticise every doctor that told me it was “just anxiety”. Because that just wasnt true, i cant make this millions of symptoms(cfs, pots, mcas…) from my head we all get that. But, why when i was in malta last week, just enjoying my time, no symptoms showed and most importantly no chronic fatigue, i could walk the whole day. When i was then back in Vienna with all of my obligations, the symptoms wete waiting for me :))