just fight ppl.
pretty good workout for fighting.
in my boxing gym when i grew up it was 80% sparring, 15% bags/training and 5% running.... but everything you can learn on the bag/training you can learn sparring, depending on who you are sparring with and what the purpose of the session is.
nothing builds fighting muscles like fighting tho.... seriously... i know it sounds stupid and im prepared for the massive neg reps but alot of ppl waste time doing workouts when they should be fighting...
JMO of course and im very biased by the way i grew up training.
go ahead and flame away.