Heart Rate Training Blunders

So it didn't all go as planned this morning. Eric Harr says you should train in the 60-70% zone. For years now I've been running on a treadmill and have gotten to where I enjoy running at about 6.2 mph for a "cruising speed". The HRM had other plans. It decided that I was going to run at closer to 5.0 mph. It actually didn't fuss much when I walked at 3.5 mph. I could not understand why it was "better" for me to slug along at a 12 min. pace. Extensive reading on the internet yielded that working out at lower intensities burns more fat. It seems kind of counter-intuitive, but the rationale is that it takes oxygen to burn fat effciently, and when you're operating at high levels, you go into an anaerobic state and the oxygen isn't there for fat burning. I want to fry all the fat possible, but I also like to feel like I'm working out. Today I didn't feel that. It's going to take some adjustment. The HRM works great though. The little heart blinks lovingly at me while I run. It just yielded some very unexpected findings.