A mate of mine does kick boxing, mind you, i aint seen him for 2 years. Last time i went to his place we was pissing about and he kicked me in the face across his lounge - bloody powerful kick, and i wasnt expecting it.
Kickboxing is great fun though.
I dont really exercise, the only exercise i get is walking to the bog when i need a piss, or using the cluch pedal on me van.