He said: "It is getting more and more likely I will never play with another team.
"When I left Ajax I told the supporters I wanted to finish my career there and that was the plan for a long time.
"But at 34 I got a chance to play at Old Trafford and here I am competing for big trophies and part of a fantastic team. That is not something you give away easily.
"I feel fine. I had small groin strain over Christmas but I've recovered from that and I am ready for the last four months of the season."