Interval training.. Do 4 minutes of high paced (not all out) cardio (treadmill, eliptical, bike) then do a set of weights (does not need to be heavy, just enough to cause exertion) and then jump back onto another cardio machine (mix it up) then another set of weights. I do 3 sets of upper body weight exercise and 3 sets of lower body exercises. I also completely change the routine each week. Every 3rd week or so I do mostly cardio with box drills in the gym mixed with some resistance/weighted ball stuff. At the end of your workout eat some lean protein or a protein shake within a half hour or so.
I used a personal trainer at my gym for about 4 months to get all of these routines down. I actually gained weight the first 4 weeks and then once I made it over the hump the weight came off super fast. My sleep patterns improved vastly and I had more energy during the day. Last winter I fell off the exercise cycle and am almost starting over from scratch, I am just about to break over the hump again.