Hi, Pooks - I've gone from "obese & sedentary" to "fit & muscular apple" and the heart rate monitor really helped - I haven't ever used it riding on the road, but all the time in spin classes at the gym. I could target my workout for cardio training OR fat-burning. Without the monitor, it was really easy to get "pumped" and go too high during the workouts when I wanted to burn butter. At the gym everyone pretty much uses Polar - I picked up a Reebok monitor at a big-box store and it never worked right and now I have a Polar, too. The monitor is great, but it was important to have a good trainer who could watch me and readjust my target numbers as I became more fit. Because I was still a big woman, most trainers assumed I still had a low fitness level and had me doing WAY too little. So yes, treat yourself to the monitor and learn more about your body!

Regarding your distance question, I think it's trying to compare apples and oranges, and that is NOT to put down the beginner's miles at all - I'm still a newbie myself. I think those beginning miles/laps the toughest you'll ever do. When you're beginning the awesome journey of fitness, you make all kinds of new demands on your body and psyche. It takes a lot of energy - and not just the caloric kind. Why compare your workout to another's? I believe a 300lb woman can go to the gym, work out with good focus, and have a better, higher integrity workout than the seeming athlete next to her who is being sloppy.