Punchbag!

Hi folks, got myself a punchbag this weekend and I am loving it. Today I just worked out for 30 minutes doing various combinations of jabs and hooks with the odd kick... Checked my heart rate at the end and it was around 140 but I had had cooled downa little bit and got my breath back by the time I got round to checking it. Very basic but I felt fantastic after. Anybody have any ideas of a more organised workout?