I broke through my plateau by having 2 of my 4-5 cardios/week being interval training and having my weight work be primarily slow lifting with very heavy weights/lo reps and consistently increasing the poundage of my weights. I also include endurance weight work but it is predominantly lo rep/heavy weight. I swear by this for me but everyone is different. In addition, to two interval cardio workouts, the other cardios are kept varied as you can get pretty used to your cardio routines and it is much more difficult to get your heart rate up compared to where you initially were able to get it up to, if you don't vary the workouts and style of workouts. I include step (lo step, hi step), kickbox, hi-lo and circuit.