Rio: I want to give United my all
Ferdinand, 34, announced his international retirement on Wednesday - ending any lingering hopes of a playing at the 2014 World Cup in Brazil.
"I think I owed it to Manchester United to do that but it wasn't easy, I'm not going to lie," he told MUTV.
"To put that to one side is a big decision and a hard decision but when your body says you need to put something aside to keep yourself in good condition for your club, which is your day to day job, the decision has to be made.
"I'm as passionate as the next man and I've always loved doing that. But there comes a time when your body tells you what to do.
"If I want to remain fit and well and playing consistent football at the top level it had to give somewhere and international football was that.
"I had a good stint in international football but now I want to give my everything to Manchester United."
Although he had yet to play under Roy Hodgson, the prospect of the United defender adding to his 81 caps did seem possible, despite the confusion over his recent call-up and subsequent withdrawal from the World Cup qualifiers against San Marino and Montenegro due to an "intricate and pre-planned training regime".
Ferdinand had earlier issued a formal statement, in which he urged England to put their faith in the current crop of younger defenders. With Ferdinand and John Terry, for so long mainstays of the side, both now retired there is room for others to grow and Ferdinand will be behind them all the way.
"After a great deal of thought, I have decided the time is right for me to retire from international football," Ferdinand's statement read. "At the age of 34, I feel it is right for me to stand aside and let the younger players come through, which allows me to concentrate on my club career."
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