He got the injuries of Michael Carrick, [Marouane] Fellaini, [Paul] Pogba and [Ander] Herrera - basically all of the midfield players I have.
"There comes a time when your body tells you it is time to stop".
"It's fine, it's something you've got to accept so that is where I'm at".
The former England global said that a move into coaching at Old Trafford was "looking likely".
He became a Champions League victor when United saw off Chelsea on penalties in Moscow in 2008 and, although he lost subsequent finals in Europe's top competition against Barcelona in 2009 and 2011, last season's Europa League triumph completed an individual clean sweep of major domestic and European club trophies.
Carrick has made three appearances in all competitions since returning from the heart complaint, but the skipper is still hoping to have a say in United's fortunes before calling time on his playing career.
Tremendous positive energy, warmth & genuine affection at Sonia Gandhi dinner: Rahul
Left and TMC leaders present at the dinner said that it was certainly a "political dinner without political talks". Lalu's son and Leader of Opposition in the Bihar Assembly Tejashwi Yadav is also likely to attend.
The 36-year-old is the longest-serving player at Old Trafford, having joined from Tottenham in 2006 and gone onto win the Champions League and five Premier League titles, among many other trophies.
"I remember him clearly in the dressing room, in the meetings eating every word, listening to everything".
"I need to keep myself fit and ready".
"It started in the Burton game and then happened again in training", he added, quoted by Goal journalist Kris Voakes.
Carrick, the club captain, had a cardiac ablation six months ago after he discovered that he had an irregular heartbeat.
"I wanted to finish on my own terms so I was determined to get back fit".
"I don't know (if he can play), we don't know yet, but he trained a little bit after you left".