The Argentina captain, after spending 21 years at Barcelona, moved to Paris last summer and only contributed 11 goals and 14 assists for the Ligue 1 champions in his first season.
Messi has already netted six goals and assisted eight times in 11 appearances this term and said his revival is down to a different mentality.
"Last year, as I already said, I had a bad time. I never finished finding myself and this time is different. I arrived with a different mindset, more adapted to the club, to the locker room, to the game, to my teammates. The truth is that I feel very good, and I'm enjoying myself again."
He scored twice in Argentina's victory over Honduras in Friday's international friendly in Miami to extend their unbeaten run to 34 games.
Messi, 35, will play in his fifth World Cup in Qatar and Argentina head into the tournament in high spirits after winning the 2021 Copa America, their first major title in 28 years following past disappointments.
"I'm very eager, excited and anxious for it to arrive," he added. "But at the same time, I'm calm because we know there is still some time. We have to do well at our clubs to arrive at that point in good form. We have a great team, a great group, the World Cup is special, and we have to take it one step at a time."
Argentina will be hopeful of Messi avoiding injury before they begin their World Cup campaign against Saudi Arabia on Nov. 22 but the forward said he will not alter his game.
"There are many games and little rest time, but you have to face it as always," Messi said. "If you are going to play thinking about the World Cup, taking care of yourself or avoiding contact, in the end it could be worse.
"I am one of those who thinks that things happen because they happen and if things have to happen, they will happen. God willing, nothing happens to anyone, and we can all arrive as we are."
Argentina coach Lionel Scaloni is also delighted that his star player has rediscovered his best form.
"I think that PSG have found a way to play that understands him and I think he has taken a step ahead in his team," he said earlier this week. "We are very happy with how things are currently going."
Following the win on Friday, Scaloni added: "The important thing is that he [Messi] is comfortable and that he is enjoying playing football. He is enjoying playing for his club and that is important. When he enjoys it, we all enjoy it. May it continue."