So I ran.
I tried to do a little bit of interval running (or tempo, still figuring out the difference). For the first 25 minutes, I would do a slow job for one song, then a quicker run for the next song. After that, I just slowly upped my speed every few minutes.
I ended up doing 4 miles in 40 minutes. And now I know I nice flat 4 mi course! :-)
Tomorrow is supposed to be hills, 5-7 miles total (so warmup, hills, cool down, etc.) I'm starting a free trial at T's gym as well.