The midfielder struggled to establish himself under Louis van Gaal, and Jose Mourinho offered him little game time either.
Despite being a France international, United’s £24million signing in 2015 found himself behind the likes of Michael Carrick, Ander Herrera, Marouane Fellaini and Paul Pogba.
As a result, Mourinho offloaded the 27-year-old to Everton in January, and Schneiderlin is now rediscovering his joy of football at Goodison Park.
But things became so tough at United, he even stopped going to Old Trafford for matches when not selected due to the difficulties of dealing with supporters and not being on the pitch.
Morgan Schneiderlin left Manchester United for Everton having struggled for game time
It was painful. I couldn’t go there, smile, and sign autographs for fans
“It was different at Manchester United,” Schneiderlin told The Times. “My routine would be the same as yours. I was used to playing football and then I was waking up as a spectator.
“I will be honest, there was one point in December when I did not go to matches any more because it was hard.
“It was painful. I couldn’t go there, smile, and sign autographs for fans and pretend to be happy when I was not. For me it was better to watch the game at home.
“I remember the best thing ever was after Stoke [City on February 1] when I had made my Everton [full] debut.
How Man United could look after £250m summer spending spree Thu, April 13, 2017
Is this how Manchester United could look if Jose Mourinho goes on a £250million summer spending spree?
Play slideshow Getty Images 1 of 12
Get Quotes on Home Insurance
How Manchester United could look if Mourinho splashes out this summer
Mourinho opted for a host of midfielders ahead of Schneiderlin at Man United earlier this term
“You walk and your calves are heavy, your quads are heavy and you feel like you need to go to an ice bath. That is the best feeling ever.
“When you are feeling great every day, and you don’t have any knocks or anything, is when football starts to get boring.”
At Everton now, Schneiderlin has returned to being a focal figure of his team, and is expected to start at home to Burnley today (3pm).
The Toffees could even finish above Manchester United yet in the Premier League table, with only three points separating the two teams chasing European football.