DUDE! You need to understand what you need to do, to accomplish the results you want. AS you wish to lose weight and gain aerobic fitness, I suggest you study the Lydiard method of training for distance runners. Consult with your Track Coach who can help you assess your current fitness level and design the appropriate component workouts in each of the three training phases. Then use your GIANT MANLY BRAIN (thanks, Peg Bundy) to exercise discipline to accomplish your goal. Nine months from now, you'll be glad you did! Come on, now...you are making us old guys look BAD!