With LC it's difficult when you get POTS, i.e. my resting HR was 60 and the moment I stood up it shot to over 150, making me dizzy and super unwell. Rowing machine and electrolytes helped quickly though. Also, post-exertional malaise (PEM) is real, when I overdid it with sport on my good days, I paid by a week in bed unable to move. Pycnogenol/OPC turned out to be a great help with that.