Keith's idea may work well for you. Not only keep track of your weight, but keep a log of how far you have walked or cycled, what your resting heart rate is, dimensions of various parts of your body (you know what I mean!!), how much you ate, and also how well you slept.
Look for modest improvements to keep you motivated....see if you can keep adding 10-15 minutes to your rides or walks each week. See if you have to cinch your belt a little tighter from month to month. Maybe your RHR will go down. These are all little things but in reality, it's the little things that will keep you motivated. And by measuring a numner of little things there is usually some good news....maybe you might stay at the same weight for a few weeks, but then you also managed your first 1 or 2 hour ride......focus on the positive. And settle in for the long-haul.
I use fitday.com to track my weight and calorie consupmtion. I use my Polar 710 HRM and software to track time spent exercising, resting HR and other acheivements. This is just what works for me. I tried similar things before, but this last time everything just seemed to click. I started with a plan of what I wanted to do exercise wise each week and just kept going from there. This might not work for you, but it's worth a try.
There are other treatments for sleep apnea......but losing weight is probaly the safest and most convenient way to go. Although weight is not the only cause of that condition. Have the test as it may not even be sleep apnea. I had a sleep test a few years ago as I would wake up often with headaches. My doctor thought it could be apnea. Turns out it wasn't and I never really found out why I had those headaches.