Rooney discusses Ferguson's impact at United in his new book, 'My Decade in the Premier League by Wayne Rooney', which is being serialised in the Mirror.
"The manager's office is right in the thick of things at United's training ground, upstairs from the changing rooms, next to the canteen.
"If someone was to wander into the club at lunch on a Monday without checking the football results first, they'd know exactly how United have got on just by taking a look at the manager's body language.
"As he buzzes around the dining tables at lunch, having a crack with people, chatting, joking (or not chatting, not joking), it's written all over his face.
"If we've won he laughs with everyone; he talks about the last game and gets excited about the next.
"If we've been playing really well, he tells unfunny jokes and shouts out silly trivia questions while we eat our lunch or get changed.
"'Lads, name the current players from the Premier League with a World Cup winners' medal?' he'll say.
"He keeps us guessing for ages. I don't think he actually knows the answers half the time.
"If he does, he never gives them to us when we pester him afterwards.
"When he's in a really good mood, the stories start.
"He goes on about his playing career and the goals he scored as a striker for Dunfermline and Rangers.
"When the atmosphere around Carrington is good - when we're winning - I can go into the manager's office whenever I want, just for a chat.
"I like going in there. It's a big room, bigger than some dressing rooms I've been in.
"A huge window overlooks the training pitches so he can see just about everything that's going on.
"The only time I don't like going in there is when I've been called up to see him.
"That usually means he's unhappy with something I'm doing, or not doing, and it always happens when training has finished for the day."