slowly coming to a better understand how what cardio's really about

i had long thought it involved running until you were out of breath (so, lung-related) and in pain (not long for me) but it seems the key is more just getting your heartrate into an elevated state for sustained periods, which ime is not necessarily painful

that is much less intimidating. i still dislike the spin bike thing i'm doing (it tires my legs and is boring) but it's not traumatic like running's always been.

what i wonder now is if working on this heart stuff will in turn make actual running easier?