The United playmaker made just one substitute appearance in two and a half months earlier this season as he struggled for fitness and form following his arrival from Borussia Dortmund.
But, as the Armenian prepared for United's home game with West Bromwich Albion on Saturday, the 28-year-old claimed he was never concerned about his place in Jose Mourinho's plans.
"Our life is worthless without difficulties," Mkhitaryan said. "Every person must be able to handle difficulties and the same concerns me.
"But it was not difficult for me to overcome these difficulties as I knew that sooner or later I would get my chance and I would use that.
"Yes, there are cases when a person faces much tougher problems, but he or she must be ready to face them. I just waited for my chance. I worked and I worked hard, waiting for my chance, got it and used that."
Since being replaced at half time of his first league start, against Manchester City in September, Mkhitaryan has emerged as an increasingly influential figure in a United team that has won the League Cup and is still hunting success in the Europa and Premier Leagues.
And, having scored in Armenia's World Cup qualifying win over Kazakhstan at the weekend, he could return to the starting line-up for the visit of West Brom, having been on the bench for United's last outing, a 3-1 win at Middlesbrough two weeks ago.
- Injury trouble -
United midfielder Paul Pogba, who suffered a hamstring injury in the Europa League win over FC Rostov, has not recovered in time to play and is one of five senior players unavailable for the return to league action.
Central defenders Phil Jones and Chris Smalling, both injured while on international duty with England, will also be absent, while Zlatan Ibrahimovic and Ander Herrera continue to serve suspensions.
"So we lose four and I think Paul Pogba is also out. So we lose five. So we are in a bit of trouble," said Mourinho, whose team are four points behind fourth-placed Liverpool in the race for Champions League qualification.
"I don't know how but both central defenders got injured in the English camp even before the match. The match was on the Sunday against Lithuania and they were injured in the training session."
Having beaten Arsenal 3-1 in their last game before the international break to move to 43 points, West Brom's only significant concern is the form of leading striker Salomon Rondon.
The Venezuelan ended a 15-game goal drought this week when he scored for his country in a 3-1 defeat to Chile but is likely to be a substitute at Old Trafford.
With Rondon not due back from his international travels until 48 hours before kick-off, he is expected to be held back for the midweek trip to Watford with Wales forward Hal Robson-Kanu in line to start against United.
"He's been disappointed he's not been playing," Albion manager Tony Pulis said of Robson-Kanu.
"He's made me aware of that. Every training session he's been first-class and when we win games there's no one happier than him.
"He's been a real stalwart in respect of his experience and character.
"Most clubs I've been at, you know you get it right because the people out of the team are still really competitive and hard-working for the team."