nothing beats just plain roadwork.
me, I do 2.5 - 3.0 miles (100+ stories) on a stairmaster 2 times a week. I try to maintain between a 7 and 8 mile and hour pace. varies depending on the day.
there is a difference between aerobic and anaerobic (sp?) conditioning though. I've recently seen a 17 year old dude that ran rings around me in stand up sparring not be able to go 2 minutes on the ground with someone close to his size.
best anaerobic conditioning is rolling and rolling and rolling and rolling and rolling and rolling and...well you get the point.
"George never did wake up. And, even all that talking didn't make death any easier...at least not for us. Maybe, in the end, all you can really hope for is that your last thought is a nice one...even if it's just about the taste of a nice cold beer."
"If you find the right balance between desperation and fear you can make people believe anything"
"Is enlightenment even possible? Or, did I drive by it like a missed exit?"
It's simpler than you think.
I could be completely wrong"