Guardiola admits he's struggling with his diet and sleeping habits.
He told Amazon Prime: "Sometimes you don't need to have a great team to be happy.
"There are no players or coaches who don't play for months because the results aren't good. All that is normal and can happen.
"I am a person who sometimes gets nervous, I have bad days, I make a lot of mistakes and rudeness makes me nervous.
"Do I sometimes lose my head? Yes. I sleep worse and I don't digest food properly now. I always have to eat light. Only soup at night.
"But I am the same coach as five months ago, the one who won the Premier League title.
"If I'm in a bad mood, it's bad. But I know it will pass. The same when I'm very happy. I know it will pass.
"I sincerely believe that it will be a year of great difficulties. We have to find continuity.
"But if we manage to get through to the Champions League, it will not be easy for anyone to face us."
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