like the guy up their said you wana punch and kick the heavy-bag but be sure to use technique rather than put in a flurry of punches and kicks. act like the bag is a person not a defensless bag. move your head after punches and change levels body head body head when you punch. switch it up by only punching with 1 hand per round.
jumping rope is a good cardio exercise dont underestimate it.
shadow boxing is very important
use small dumbells 5 pounds at the largest for atleast 1 or 2 shadow boxing rounds and when you use dumbells be sure to work on your punching technique not speed and power. go slow use your shoulders.
i hope this helps a little oh and btw be sure to time your workouts by rounds 5 minutes is a good one.