What is a good cardio boxing routine?

I hold the focus pads for my girlfriend and need to keep the routines interesting and challenging. Has anyone taken any cardio-boxing classes and can share the routines used there?|||I have a heavy bag and i will do rounds like say a 2 or 3 minute round where you just jab then rest 1 minute then do another round where you do hooks then rest and so on. For a challenge what i do instead of resting in between rounds i also have a speed bag so i do 1 round the go to the speed bag for 2 or 3 minutes then round to and so on. Its a great work out really works the whole body. If you want to try the speed bag get the large one for beginners then move to the small one. there not as hard as it seems. punch on that speed bag for 5 30 minutes and tell me if your arms and traps and shoulders dont burn.