Sebastian Vettel says he is "at peace" with his poor season at Ferrari last year and "excited" about starting work with his new Aston Martin team.
The four-time champion said he had "high expectations" as the Aston Martin name returns to F1 for the first time in 60 years.
Vettel said: "I am not happy with last year in terms of performance - partly my performance - but I accepted it.
"There are things that didn't go well, but I am looking forward to this year."
Vettel, who learned he was to be dropped by Ferrari before last season even started, said Mercedes "had to be the favourites" for 2021 and that Aston Martin - formerly known as Racing Point - had an "unofficial, or maybe official target" of finishing third.
They were pipped by McLaren to that position at the final race of last season.
A champion moves on
Vettel, winner of 53 grands prix and one of the most successful F1 drivers of all time, said he had nothing to prove after his disappointing final two years at Ferrari, in which he was out-performed by team-mate Charles Leclerc.
And he said he was confident he was still capable of winning another championship if he has a car capable of it.
"It's not a secret that at stages last year I was not at my happiest," Vettel said. "This year I am very much looking forwards.
"Things are a bit different but from what I have seen the people are very capable and talented and it is the first time for the last few years that they are getting the oxygen to breathe."
That remark is a reference to the increased budget the team has been afforded under owner Lawrence Stroll, as well as the fact that a budget cap has been introduced into F1 for the first time this season.
Why are Aston Martin in F1?
The new car was unveiled online with contributions from celebrities such as James Bond actor Daniel Craig and NFL star Tom Brady.
Canadian billionaire Strollrescued what was then known as Force India from administration in 2018 and renamed it Racing Point.
The 61-year-old last year took over the historic but struggling Aston Martin sports car company and decided to rename his F1 team after the brand to promote it around the world.
Stroll told BBC Sport in January that his ambition is to turn the team he owns into title contenders and at the launch he said the team's "ambitions were limitless".
Vettel's team-mate Lance Stroll, Lawrence's son, paid tribute to the transformative effect his father has had on the team, which until he took over was notable for overachieving on one of the smallest budgets on the grid.
Lance Stroll said: "He has given the tools to the incredibly talented people in the factory. Now we can move forward and there are exciting times ahead of us.
"The potential is there to fight up at the front, perhaps even challenge Red Bull. Mercedes are going to be very difficult because they are a bit further up the road and hopefully we can increase the gap over the teams we were fighting last year."
Vettel described Stroll as "very quick" and said that some of the criticism the Canadian receives, which is often based on the fact he drives for his father's team, was "not fair".
What's the car like?
Technical director Andrew Green and team principal Otmar Szafnauer said they believed it would take between three and five years to build the team into title contenders.
Vettel said: "It is a journey everyone is excited to embark on but we are not expecting to arrive tomorrow.
"If we do, I don't think anybody minds. But it is not going to be that easy."
The Aston Martin car bears a strong resemblance to a Mercedes - as the 2020 Racing Point did.
It features the 2020 Mercedes gearbox and rear suspension, which Aston Martin buy from the world champions in addition to their engine and use of their wind tunnel.
This suspension was regarded as a major development step for Mercedes last year because of the amount of potential aerodynamic downforce it unlocks, and could prove to be the same for Aston.
The fact that Aston Martin was allowed to take on the 2020 Mercedes rear end was a controversial topic last year because development restrictions have been imposed on teams this year on cost-saving grounds.
Rivals saw Aston buying these parts from Mercedes as a 'free' upgrade when others are limited to just two 'tokens' on changes to mechanical parts of the car, but governing body the FIA rejected their complaints.
Aston Martin have been able to spend their two tokens on top of the suspension change, and have chosen to update their car's monocoque. As such, their car arguably has the potential to be a bigger change from last year's design than any other on the grid.
Green said the team were confident they would be able to give Vettel a car that had handling characteristics that enabled him to perform at his best.
He added that he believed the team's new car, which is scheduled to run for the first time in a short test at Silverstone on Thursday, with both drivers taking a chance at the wheel, was "a solid foundation to work off".
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