I'm in awe of your dedication. While you've got a large mountain to climb, every step brings you that much closer to the summit.
I will second N7CZinMT's recommendation concerning the heart rate monitor. This little device will help you lose weight by guiding you to the optimal fat burning rate (usually 60-80% of your maximum heart rate). While you're at it I recommend picking up the following book as a companion to the HRM;
link here
Best of luck!!
-mark