Lewis Hamilton says he can still get better as he embarks on the weekend when he should clinch a sixth Formula 1 drivers' championship.
Hamilton is almost certain to seal the title at Sunday's US Grand Prix, needing only to ensure he does not lose 22 points to Mercedes team-mate Valtteri Bottas.
"I never thought I would have five titles. If I am able to get a sixth one, it will be pretty unreal," Hamilton said.
"I don't think I've hit peak yet and I plan to continue to get stronger."
Hamilton emphasised that "nothing is a given" and that he is "approaching it exactly as I have all year, one race at a time".
The only way Bottas can keep the championship alive is to win the race - and even then Hamilton only has to finish eighth to secure the title.
The 34-year-old Briton has won the race at the Circuit of the Americas near Austin, Texas five times in the seven years it has been on the calendar.
"Austin has been a good race for us in the past," Hamilton said. "It was not so good last year, but it is a good hunting ground in general and I am going to be pushing very hard this weekend to finish where I plan to finish.
"But it's going to be a challenge again with the temperatures and the wind. I can't tell you how it would feel but I approach every year as if it's the first and it'll be the same next year."
Austin is experiencing unusually cool temperatures. Thursday was said to be the coldest Halloween for nearly 30 years. Overnight lows are close to freezing. That is expected to create difficulties for the drivers to get the Pirelli tyres up to the right operating temperature.
Hamilton said he believed 2019 had been one of his strongest seasons, and pointed to his race performances as a highlight.
"I've only had four poles but I've had 10 wins," Hamilton said. "Within the team, we often forget how many wins we've had because we are so focused on each race and we forget how well the season has gone because it has felt so hard.
"But definitely when you look at the numbers, it is a good feeling. Hard work pays off and the guys have collectively worked harder than ever.
"Every year we try to get better, we try to apply ourselves better and balance our energy levels better, communicate better, so we deliver consistent results collectively. It's great to look at the results because it reflects the improvement we've made.
"I would say Sunday [race day] has been the thing I have been most proud of, it's been stronger than last year and that's good to see.
"The goal has been to try to keep the consistency from last year and build on other areas and the race was one of those and we have been stronger all year throughout the races. There are areas we can still improve on."
Hamilton gave the strongest hint that he will be still be in F1 in 2021, when the new regulations announced by the sport on Thursday come into force, and that he will likely stay with Mercedes.
"Nothing is set in stone for the future but I am definitely enjoying what I am doing and I don't see any reason to stop because I love what I do," he said.
"I don't see myself going anywhere else. I love being here at Mercedes. I love being a part of the brand, of the history, and the idea of staying with Mercedes, I have been with them since I was 13.
"The idea of continuing on with them even beyond F1, probably heavily involved within Daimler, is quite attractive."
Hamilton comments 'a bit disrespectful' - Verstappen
Meanwhile, Red Bull driver Max Verstappen criticised Hamilton and Ferrari's Sebastian Vettel for their remarks after last weekend's race in Mexico.
Hamilton, who collided with Verstappen at the first corner, said he had expected he would be "torpedoed by Max" at some point and he always gave him extra room compared to other drivers.
Verstappen responded on Thursday in Austin, by saying: "Looking at Turns One and Two in Mexico, I don't think that happened. It was a bit of a silly comment to make. I think I'm always a hard racer but fair.
"It's just not correct - but of course it's easy to have a dig at someone. From my side, it's fine. It's always positive when the talk is about you. That means you're in their head."
He added that it was "a bit disrespectful and I prefer to fight on track and of course I like to fight hard but on the edge. If they want me to stay behind, it's better to stay at home. I really want to take the fight to them because that's what we are here for. We fight for victories because that's what we live for."
Hamilton said in response: "I was explaining the scenario. I don't think it was disrespectful in any way. There wasn't any fall-out. It was a great race and a great weekend."