Originally Posted by b0redom
You don't need to be particularly fit to start kickboxing, you'll probably find that it works different muscles though. The most important thing is flexibility so you need to do plenty of stretching.
It's been a while since I did it, but I loved it - presumably it's semi-contact. Continuous sparring with all the gear on will cause the weight to drop off. I was reasonably fit, but couldn't keep it up for 3 mins - are you using full size gloves on the punchbag?
Adidas bag gloves with a free standing punch bag.