This is an awesome conditioning workout that you can do that will do the following:
The exercise is 3 3-5 minute rounds.
Warning: I know to some of you this may sound like cake, but after a minute of hitting the speed bag intensely, the seconds start ticking noticeably slower.
Don't forget that as one blocks, the other one hits. Start slow until you develop the a consistent pace. This is a skill that develops over time.
Challenge: Try to hop as you hit the speed bag for an increased cardio workout.
In this video Chris is using the EZspeedbag -- a door-mounted speed bag that also doubles as a pull-up bar, but it should be noted that this exercise can be done with any speedbag. Remember that the smaller the bag, the higher difficulty it is.