Do You Exercise Even When You're Sore?

I found a new running buddy in my neighborhood, and let's just say that she's much more hard-core than I. I led her through a leisurely 35-minute run, and the next day, it was her turn to lead. She had us running up every hill in the woodsy trails near our homes. By the end, we had run for over an hour. The next morning I woke up to extremely sore legs and a phone call asking if I was up for going again. I had to pass, saying I was way too sore to even bend over and tie my sneaks.

Exercising when I'm a little sore often relieves my tightness, but when I'm so sore even walking hurts, I skip the workout and rest. What about you?