Amorim added that the strain of managing United, considered one of the toughest jobs in the Premier League, had taken its toll on him.
"You can see in my face, you can compare the way I arrived and now," the Portuguese said.
"Of course when you are (losing) there is a lot of pressure. It is hard to cope with all the problems, the bad performances and the losses, it is really hard.
"It is supposed to be really hard. The only thing that can help me is training with the players and I also have my family now here so it's so much different, it can help me."
After their clash with Liverpool, United travel to face Arsenal in the FA Cup on January 12.