Andy Murray set his sights on remaining top of the world rankings next year, but acknowledged the difficulty he faces in doing so.
The Brit held onto his spot as world number one with a 6-3 6-4 win over Novak Djokovic in the ATP World Tour Finals decider on Sunday.
The title was his ninth of the year and extended his winning run to finish 2016 to an incredible 24 matches.
Murray, who won Wimbledon and Olympic gold this year, said it would be tough to retain his place.
"I would like to try and stay there, obviously. It's taken a huge effort the last five, six months to get there. I would obviously like to stay there," he said.
"I'm aware that's going to be extremely difficult because I had a great year this year. I only managed to do it by one match.
"To repeat that again next year is going to be extremely difficult. But now that I've got there, I obviously would be motivated to try and stay in that position.
"But the majors are what gets me working hard and what really, really motivates me. When I go away in December to train, I'm training with the Australian Open in mind.
"Because of the best-of-five set matches, they're the ones you have to really put in the extra work for and the extra training for. That's what motivates me."
Murray capitalised on an error-riddled display from Djokovic in the final, winning in one hour, 43 minutes.
While the three-time grand-slam champion was pleased, he felt some of his previous battles with his rival were much better.
"I don't think that was one of Novak's best matches. I think we have played better matches together," Murray said.
"The end of the match was exciting and dramatic, but there were mistakes from both of us. I think I've probably played better matches.
"I was solid enough when I needed to be. I didn't make those mistakes. I think although I maybe made a few more mistakes than I would have liked, I think tactically I played a good match. It was obviously a good performance.
"You never beat a player as good as Novak if you don't play well. I'm not suggesting I played a bad match. I just think the two of us have played better matches than that one."