The Hull City boss played at Old Trafford for nine years between 1987 and 1996, winning three Premier League titles and three FA Cups under Ferguson before embarking on a managerial career of his own.
He says his former boss is always willing to offer encouragement - as he did ahead of Hull's promotion clash against Cardiff last weekend - and says his drive to succeed has had an impact on everybody who has worked with him.
Bruce told Sky Sports News: "Whoever has gone to play for him, this winning mentality that he's got rubs off on you. People ask over the years what he's like and he's so driven and so determined and he works so hard at the job.
"When you finish and you hang up your boots it's no surprise that a few of us have gone into coaching. He sets such high standards that he's very difficult to follow. It's impossible to copy somebody like him.
"He wants to beat you for certain and he does that constantly with us, but he offers you a bit of encouragement. He's always there if you pick up the telephone and he'll always come back to you.
"He's got a humility about him from his working class background where he'll treat the groundsman just as well as he'll treat his star centre-forward. He's got a fantastic humility about him for all he's achieved.
"I spoke to him a couple of days ago and there was no hint of anything about retirement. There was a simple text message and a short conversation wishing me good luck for the weekend and afterwards a text to say well done.
"He'll do that not just with his players who've gone into management, but he'll do that for most managers, especially the young ones. He'll always give you the encouragement that every young manager needs."
David Moyes has been installed as the favourite to take over at Old Trafford and Bruce says the Everton boss is a worthy candidate.
But he says Ferguson's shoes will be almost impossible to fill after producing a list of accolades that includes 13 Premier League titles and two Champions Leagues.
"Whether it's Jose Mourinho or David Moyes or whoever, I know one thing, it's going to be some act to follow," Bruce added.
"When you look over 27 years at the trophies he has won it doesn't seem quite right that Fergie won't be in charge of Man United any more.
"He has gone on and on and on and 27 years is quite remarkable - and I can assure you I don't think the next manager will do 27 years.
"It's quite incredible that Sir Alex has been in charge all that time and it's an unbelievable achievement. To have 1500 games in charge of Manchester United is, in itself, a record I don't think will ever be broken.
"It'll be not quite the same and it'll be difficult for whoever goes in because he's such a big act to follow."