you should get one of those simple step machines, i have one and theyr really good, but failing that i guess you can do step ups on a box or something, its good just to do at home when everyones in bed.. i do it when i watch dvd's or fights i got and lord knows i watch a lot so i always have plenty of time to work on my legs, with the machines you can really feel it!but jogging and running and joggin on the spot is also good and move around alot when you shadow box, its helps my rythym lots at the same time as bien exercise,
hope its of some help.