Disclaimer: I am not a doctor nor do I claim to be and you should always consult your doctor for any changes to your routine or healthcare.
Many POTS patients have a very low exercise tolerance due to the nature of the syndrome. A lot of times POTS patients have exhasperated symptoms when trying to exercise which makes it very hard to continue to workout. Here is one of the great resources called that CHOP protocol that was developed specifically to help with exercise intolerance.