Have you thought about investing in a heart rate monitor? I bought a Polar a while ago on a whim and on the advice of a cousin - but before I was really motivated. I'm using it now though! It is better than the calorie counter on my treadmill - and if I decide to go for a brisk walk around the neighborhood when it is cold out, I don't have to take off a glove and feel for my pulse to see if I'm in the "fat burning" range. This morning I treadmilled, and this evening I did a cardio DVD... if I didn't have the Polar on, I probably would have worked TOO hard at the cardio and given up 10 minutes in.
Mine also tracks the calories I've burned through exercise on a daily and weekly basis, and tells me what percentage of those calories were "fat".
I seriously wouldn't exercise without one. I'm even taking it on some trips in the next couple of months... I might not have access to a gym, but I can still walk!
are they very expensive?
It is a bit of a splurge, I'll admit.... I seem to remember mine was a bit middle of the road in terms of all the models, but had some useful bells and whistles.
I got mine on Amazon (NOT from another seller on there, but Amazon.com itself). I know there are other brands, but I was told by family members (who are runners; one used to do triathalons!) that Polar was the most reputable brand.
There is a good description and some good, detailed reviews there too... this is my model: