Casemiro believes Manchester United are on a "good path" and says playing for the Old Trafford giants makes him feel like an excited 15-year-old again.
United failed to land Frenkie de Jong and Adrien Rabiot but pulled off a coup by signing the Brazil international from Real Madrid in August.
Some questioned United's decision to pay £60 million ($74 million) for a 30-year-old – a fee that could yet rise by £10 million – and even the hunger of a player who has won so much.
But Casemiro has excelled at Old Trafford and embraced the challenge of turning the club's fortunes around.
"When you arrive at a new club, you always dream of making history... especially if we see the greatness of this club," the Brazil international said after United's 3-1 victory over Reading in the FA Cup fourth round on Saturday.
"We know the history. But of course, I was aware of needing some time to adapt and of the rivals having a long-term plan before ours, like Arsenal, Manchester City and Liverpool.
"They all have managers that have been there for a while and, therefore, they have an advantage."
Casemiro said he was relishing life at Old Trafford.
"I'm very comfortable at Manchester United, extremely happy to be here and enjoying every moment like a 15-year-old kid," he said.
"But the most important (thing) is to see the team growing."
Casemiro, who scored two goals against Reading, warned that United, still fighting on four fronts, were still a work in progress.
The club are riding high in the Premier League and have one foot in the League Cup final after hammering Nottingham Forest 3-0 in the first let of the semifinal last week.
They are also still involved in the Europa League where they will face Barcelona in a two-legged, play-off tie.
"We have to see what the reality is and we are still a club under construction," Casemiro said.
"Of course we are already respected, the opponents know we're strong, that we have good dynamics, the manager is doing a good job, the players as well."
The Brazilian said he relished the chance of a new challenge under Erik ten Hag after a trophy-filled spell at Real Madrid.
"The job is on with a lot of humility by knowing there's a lot to improve, but all the players need to be congratulated now," he said.
"We're on a good path. This is the way to win titles, but we need to keep growing."