Don't ever question Mark Cuban's work ethic -- 'cause the guy was so determined to make the Mavs a success after he bought the team, he PERSONALLY cold called hundreds of people to sell tickets.
It's a pretty impressive story ... Cuban says he's all about getting in the trenches and doing the work himself if duty calls -- and back when the Mavs sucked, duty definitely called.
One other thing ... Cuban says he respects the hell out of telemarketers -- and instead of hanging up on 'em (like most people), he listens to the pitch and offers feedback!!!
Watch the clip. Take notes.