I had to stop 3 minutes into the 5 minute interval due to a stitch. I paused and finished it, but skipped out on the next 3 and 5 minute interval. I had trouble getting my whole breath with my minor cold.
My shoes feel like a cushion of air, it was really nice. The right side of my right foot was a bit soar, I think it is naturally angled like that and it hurts a bit.