The 33-year-old won his fourth world championship last season, 46 points ahead of Ferrari’s Sebastian Vettel.
Hamilton said he expected “a closer season” than his 2017 title win but would not reveal who his closest rival could be.
Speaking at the launch of Mercedes’ new car in Silverstone on Thursday Hamilton said: “It is quite simple – I want to somehow be better than I was last year.
“Last year was I think the best year I had performance-wise. How can I top it? There are lots of areas actually.
“When you go back to training, you start to work out: why am I training? What is my motivation? Where are you going to find the training and the drive? What are the goals?”
His Mercedes team-mate Valtteri Bottas laid down a gauntlet after stating he expects to challenge for a world title after finishing third in the driver’s championship last year, 58 points behind Hamilton. Mercedes are seeking their fifth consecutive constructors championship.
“He [Hamilton] was the best driver last season but there is no driver who is unbeatable,” Bottas said. “I believe in myself. I was able to show last year I could do it.”
Hamilton’s contract with Mercedes will expire after the 2018 season and he was quick to play down speculation he could leave the team he joined in 2012 and has won three world titles with.
Mercedes F1 boss Toto Wolff said he expected a new contract to be resolved “in a few weeks”.
Hamilton said: “I know he [Wolff] knows there is no-one better, so he is not looking anywhere else.
“I know there is nowhere better so I am not looking anywhere else. It is just a question of putting everything together.
“We always made it clear at the beginning that if I was to engage and look at my options I would inform them and I have not needed to.”
Hamilton was forced into a public apology and had to delete his social media accounts after criticising his young nephew for wearing a princess dress on Christmas Day.
He said: ”I have been very open with my life for several years now and it is always difficult make a change because I quite like being open.
“But we are in a strange time in the world where things are magnified more than in previous years. It is a critical time for the world.”