Yes, there have been times when I was extra-excited to go riding, specifically because I was pissed-off at someone. It cancels out that stress-related stuff which screws up your body. Whether I forget about what was making me anxious or not, I still feel mentally better about myself, and I'm convinced that it's keeping me healthier than most people. I also do it regulary - every 2-3 days - not just when I'm anxious.
I think it's especially helpful for us aspies.
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Why be a label, be yourself and keep others guessing instead. - Dee_.