Mourinho in his first spell won the Europa League before guiding the side to Premier League runners-up the following season, but the club parted ways with him in his third season after leading the Red Devils to their worst ever Premier League start in the 2018/19 season.
The Portuguese trainer who was replaced by Ole Gunnar Solskjaer last December has now revealed the difficult moments during his stay at the Old Trafford.
"So maybe it's my fault because the tendency is to close myself in a shell. Then also my fault because what people see is the 90 minutes. The way you behave in the game, the way you appear on camera. People who see me in street say: 'Oh you look younger. Oh I thought you were a little bit fatter, you look slimmer. Oh you are taller, we thought you were small.
"So I think TV changed the perspectives.
"I am what I am. I don't act. I see people acting. I don't act. Everything is natural. When I'm on the bench and don't celebrate a goal it's natural, I am focused on what is coming. It's natural when I grab the bottles of water and throw them. It's natural when I kick a bottle. What you see is what it is. If I have reason to smile, I smile. I love to smile. I cannot explain.
"I can just say that the Manchester United time was not an easy time. I always felt that to win the Europa League was fantastic and it didn't look like it was, the way people approach it.
"To finish second was even more than that [success], so probably I was feeling a little bit like: Wow, I'm working well, I'm giving everything and I'm not getting what I think that deserves.
"The only thing I can promise you is that when I have the next club, the next project, I will be so, so happy that I will walk into that press conference with a big smile. That I can promise.
"When I gave my first press conference I was asked if I was ready for the Premier League. I thought: 'What? I just won the Champions League and you are thinking that I am nobody?'
"So, I went a little bit aggressive by saying I am not one from the bottle, I am 'a' special one. But then, bang, it stayed. No problem."
