They really do know what they're doing. I ran maybe ten to twenty lengths of the track overall, and my heart was pumping like I'd been going flat out on the treadmill for twenty minutes. One thing Dan had me do knocked me out so hard in 6 lengths (3 each way) that I had to stop for about 5 minutes just to catch my breath. I don't feel like I've been over-worked, though - just worked hard.
A lot of what they have me working on is core stability - building up the strength in my core in order to be able to handle exercises that require it. Sitting in front of a keyboard all day doesn't exactly build up the muscles in your stomach or back!