Huh? Meditation? It is way easier than that. You can raise heart rate almost instantaneously by imagining that you are doing a rigorous exercise. Slowing it dow

Huh? Meditation? It is way easier than that. You can raise heart rate almost instantaneously by imagining that you are doing a rigorous exercise. Slowing it down might be more tricky because you actually need oxygen, but pausing breath with a long slow exhale will probably do the trick.