I've been going for about 3 weeks now. I got uber-sick about 10 days ago and stopped for a few days, but I picked it back up once I got better. I just started weight-training in addition to the cardio I've been doing, and believe it or not just the weight training has motivated me more than anything else. That feeling I get right after doing a strenuous upper-body workout is probably the best I've felt in the past 3 years. It hurts like hell, but it's a good kind of hurt.
As far as the workout goes, I've been doing between 30 and 45 minutes of cardio 4-5 times a week on an "Elliptical Machine" (kinda hard to explain unless you've seen them. looks like a stair-stepper, but the motion is mostly horizontal due to an elliptical flywheel that the "steps" are connected to.) with varying levels of resistance and incline to keep my heart rate between 140 and 160 the entire time (I warm up walking to the gym). The resistance and incline also give my calves, quads, hamstrings and glutes a good workout. The upper-body stuff I've been doing involves nautilus machines that do reverse-crunches, benchpress, double-chest, curls and shoulder presses. My goal is 3 sets of 15, but since I just started I've only been able to do 1 set of 10, 1 of 15 and 1 of 5-7 before my muscles turn completely to water.
When I was just doing cardio, it was kinda hard to motivate myself (the TVs in front of the machines helped though *hangs head in shame*), but the weight-training has really pushed me over the edge. I actually look forward to going to the gym and am having to hold myself back so that I don't do any damage.