McClaren, on he and his son's McClaren Performance podcast, mentioned how negative body language will be looked down upon under the new regime at Old Trafford, and that players should generate all their focus on winning the ball off the opposition rather than react with frustration.
"You have to be ready, have to be ready to train, you have to be ready to play, ready to impact as a sub, you have to react," he said.
"A lot of people now, body language arms up in the air, you've got to react to get that ball back, win that ball back, whatever situation, react quick don't think about it."
United players have also been accused of not taking responsibility for their poor displays in recent years.
McClaren though insists there can be no hiding away from poor performances though especially if there has not been a full commitment shown.
"You've got to accept the rules, the conditions, you've got to accept the consequences if you do things wrong. You've got to commit, you've got to be a class act," McClaren said, "You've got to be a class act, especially in today's football."
McClaren knows exactly how to bring success to United. He believes a key approach is laying down unofficial rules that players can collectively buy into and trusted to follow, which was carried out by previous stars such as Roy Keane, Paul Scholes, David Beckham and many more under his first spell at the club.
"When I first went to Manchester United there was hardly any rules but what they did; they did the right things and if they didn't do the right things they owned it and they suffered the consequences and accepted the consequences.
"And I think if you've got those non-negotiables around that then you can't go wrong."
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