Federer, 36, took his Grand Slams tally to 19 last season with victories at the Australian Open and Wimbledon.
The Swiss finished the year as world No 2, behind Rafael Nadal.
He has successfully overcome a knee injury that ruined his 2016 campaign and is in the form of his life.
Federer is the favourite to defend his Australian Open crown this month in Melbourne.
And he revealed exactly how his training routine has changed over the past 12 months.
“Through the injury I sustained here in Australia a couple of years ago, my mindset has changed,” Federer said.
“I probably work less, with even more quality. So it gives me more time off.
“Essentially I’m working half days if you like, because there’s no point for me to put in all the mega hours anymore, because I know I have it in the vault, I have it there if need be.
“That’s why I think it was very important for me to prove to myself at the Australian Open this year – to win those three five setters that I had. (And also win) the two five-setters I had at the US Open.
“I won all the big matches when it came down to the crunch. I know I can do it, and it’s important to stay injury free.”
Roger Federer is already up and running for the season after beating Yuichi Sugita in the Hopman Cup.
He then partnered Belinda Bencic as Switzerland beat Japan in the mixed doubles of the tournament.