Reducing Workout Heartrate

Since I started working out last week, during cardio training, I'd run my heartrate at 100%+ of the maximum heart rate (MHR). For an hour. I'm suprised I didn't have a heart attack. The MHR is based on a formula:

males: 214 - (.8)(age)
females: 209 - (.7)(age)

It's widely known that working out at about 60-65% of MHR, you'll burn 50% of your calorie expenditure from fat. If you exercise at 80-85% of MHR, this number goes down to about 40%.

Of course, when I get in the gym, I can't resist the Stairmaster/Lifecycle at 100%+ of MHR. It's a vanity thing. I get really tired at the end of the workout, and I head directly to get Mexican fast food. Well, today I just wanted to see what 80-85% felt like on the bike. It was actually fairly tiring, and it felt like really being on the bike after a while. So I did 110 minutes on my SportsArt c53u watching stage 3 of the Tour de France. Felt great.