Like Lacey, I've recently started running again. It started a few weeks ago, after some particularly fast waltzes and polkas at a Friday Night Waltz. I felt more winded then I thought I should, and I realized that I am probably just not in the same cardiovascular shape that I was back when I was running a couple miles every day. So, fueled by a healthy fear of aging and flabbiness, I went for a jog that weekend. It was thoroughly depressing how out-of-shape I was. I had to stop and walk every few minutes to catch my breath, and I was sore for two days afterwards. But after running a couple times a week for just a few weeks, I'm already much better. The last couple of times I've gone 15-20 minutes solid running without stopping, no problem. (This is maybe 1.5-2 miles, I'm not sure.) That's a very comfortable amount, so I can probably start stretching it a bit.
One of the trickiest things for me tonight, now that I can actually keep going for a decent amount of time, was reining myself in and not outpacing myself. There's this mode that I remember deliberately shifting into, at the end of one-mile runs back in high school, where I sort of just add a few extra inches to my legs and turn them loose to start to fly. It's a super fun way to end a race (though I only ever raced against myself, of course). But it's trickier when I accidentally just start doing it early on and then can't keep up my pace as well.
I also find that at my most maintainable pace, I'm running at three breaths per inhale or exhale. Left foot first for inhale, right foot for exhale. Probably about a slow rotary waltz tempo. I think the reason I like waltzing so much is that there's just something about it that's on the same wavelength as me.