Pep Guardiola says Manchester City's title bid was conceived at last summer's Club World Cup which helped clear the "fog" surrounding the club.
City are tussling with Arsenal and Aston Villa at the top of the Premier League and they made it six wins in a row with a 2-1 victory at Nottingham Forest on Saturday.
Guardiola's side endured a torrid campaign by their standards last season as a run of four successive titles came to an end in disappointing fashion.
But the Spaniard described the summer tournament, which saw them go out in the last 16 to Al Hilal, as critical to change.
"Energy, energy, energy," he said. "We lost it last season. We started to train better, compete better.
"After that we can talk about three at the back, four at the back, wingers or full-backs - that is all b*******.
"We needed energy and then you have a good environment. When we went out to Al Hilal, it wasn't the fact that we didn't win but that we were so good there.
"It was then holidays so I said, 'OK, go on holidays' but I was p***** off because we were good there, good with the guys training, good with the competition.
"The place we were in, Boca Raton in front of the beach. Everyone was happy. Made a lot of dinners, a lot of talks, what we have to do next season.
"We wanted to extend it, just to live that.
"I think there, after talking with Pep (Lijnders) and James (French), Manel (Estiarte), Hugo (Viana), Txiki (Begiristain), we turned around and said something changed. Something (you can feel).
"It doesn't mean you are going to win but that you are able to recognise the team. Now it is eight victories in a row.
"It is not easy but compete in a way we do. We have to improve, absolutely, but this mindset is better."
"Energy can go down but energy can go up. Never in our lives is it the same."
Guardiola, whose long-term future remains in the air, admits he has also been re-energised.
"It's not about you or you or you, it was something... something was in the fog in Manchester, surrounding our training centre. We missed something," he said.
"It is not switching on or off (energy). Results help. The methodology. And Pep Lijnders, James (French), Kolo Toure.
"New players, I want to help them. When you've got the same players it is, 'ah, tired'. But new players you think, 'ah, how is this guy?', and try to analyse. The energy comes from there.
"Energy can go down but energy can go up. Never in our lives is it the same.
"In professional or personal, you'll never be happy all the time but never sad all the time. You have to realise why, to realise what we missed, to come back."
