The 29-year-old Scotland international has played just 13 games since announcing he was taking an extended break from football in November 2011 after being diagnosed with ulcerative colitis.
He has since undergone several operations - the last of which took place in January - and been put on a strict dietary regime in a bid to correct his stomach condition and allow him to resume playing duties.
Fletcher was finally given the all-clear to return to training last week and on Monday night took the first steps towards a first-team comeback by playing 67 minutes of the 2-2 draw.
"I've been training for a few weeks now and the next progression is to get some match-time. I enjoyed it," the Scot told MUTV.
"The plan was to get to half time and see how I felt. Then get to 60 minutes and take it from there and, although I felt I could have gone on a bit longer, the plan was not to play more than that so I'm better sticking to the plan and not upsetting the sports science lads."
Fletcher also praised the club and his family for the parts they played in helping him get back on to the pitch after a difficult few years.
He said: "They've been great, especially the doc Steve McNally. He's worked closely with me, getting myself right and back, and the support from the club has been fantastic - from Sir Alex Ferguson to the new manager and David Gill. Everyone at the club. I couldn't ask for anything better.
"It's been tough. Luckily, I've got a great family around me - my wife, children, mum, dad and sisters. It's a great family and, if it was not for them, I wouldn't be standing here today.
"They keep me going, keep me motivated and lift me when I'm down. All these factors contributed to me standing here today on the road to recovery."