I enjoy my treadmill Nordic (here review)and started the C25K this January. But I've been walking on it since October. Don't worry about heart rate etc. just do what you can for as long as you can. If you want to do intervals, try them out. I did and found they broke up my walking nicely. I tried a few of the treadmill programs and would rotate through them, some changing the incline and some changing the speed. Then decided to do the C25K, so more running for me now (uggg 25 mins tomorrow).