OK - so here are the numbers.

I walked 15 minutes to the driveway of the school (it's a longgggggggggg driveway), so that was a bit of a warmup, really. Although I didn't stroll.

Power walked (and just plain old walked up hill) for 17 minutes up the drive, and then did 2.5 minutes roaming around the building before starting rehearsal.

So a fairly difficult walk (for me) for 30 minutes. Not bad.