North Carolina coach Roy Williams was so disgusted with his team’s lack of toughness during its 17-loss 2009-10 season that he brought back an old-school conditioning program that included the same grueling outdoor track workouts that Michael Jordan and James Worthy sweated through in 1981.

As a result, re-focused UNC won 29 games before losing in the Elite Eight last season.

And as a result of that, Williams pushed this preseason’s conditioning program back inside.

“At Virginia [last season], a lot of years we would’ve lost that game, but were just tough enough to hang in and win. At Clemson, we were just tough enough to hang in and win. … This team I feel like has got some of that toughness,’’ Williams said at ACC Operation Basketball recently. “And the other thing is we really toughened them up mentally -- but did we have them as basketball ready, shape wise, conditioning wise? Perhaps we didn’t, so we went back to more on-the-court conditioning to try and get them more ready to play basketball.”

That on-the-court conditioning wasn’t exactly easy; players still had to run a dozen 33s on a basketball court under a certain time limit as a final test. But it sure beat the plethora of 200-meter track sprints (with only 90 seconds rest, in between) that the Tar Heels had to complete a year ago.

And Williams made sure the players know they can always go back to the track -- if they don’t stay on the mentally tough track.

“Z [Tyler Zeller], Harrison [Barnes], Justin Watts and Kendall [Marshall] all came and talked,’’ Williams said. “I said, ‘Hey, if I do this, then there better not be a time when I think you’re just giving in easily. If that’s the case, I have 20 hours a week -- that doesn’t mean we have to spend 20 hours shooting.’

“… I think there’s always the fear that during Christmas exam period, we can go out there and do it again if we need to.”