He said: “I’m proud of my time here. It’s been a fantastic period.
“Sir Bobby [Charlton] has been a great supporter of me since the day I arrived and he knows I appreciate that.
“To look at the future and how far we can go is very difficult.
“But I feel far better waking up every day looking at the team than I did two years ago when we got a lot of criticism.
“It doesn’t matter whether you deserve them, no-one likes criticism and it drives you on.
“The only way you keep your head above water is to keeping winning.
“Winning things is a sign of being a really good team but you’ve got to win things – the Premiership, Champions League and FA Cup.
“You have to accept that challenge here. Manchester United give me every challenge I could possibly wish for.”