The 20-time Grand Slam title winner and former world number one has not played since a quarter-final defeat at Wimbledon almost a year ago.
He then underwent a third surgery on his knee while his world ranking has slumped to 50, his lowest in 22 years.
Federer told Swiss broadcaster SRF that he "plays from time to time" with his four children, but "things are moving slowly".
He still intends to return to action at the Laver Cup in London at the end of September when he will have already celebrated his 41st birthday.
"I had surgery at the end of August and people ask me 'So, how does it look?'. And each time I have to answer that it will take a little more time," he said.
Federer said he is "currently focusing on (his) physical condition, so that there is no overload" and goes to the gym "five to six times a week."
"I just have to stay patient, I'm making constant progress."
After the Laver Cup from September 23-25, Federer has already said he intends to play in his hometown tournament of Basel from October 24-30.
Federer, the winner of 103 trophies over his career, played only 13 matches in 2021 and just six in 2020.
ATP Roger Federer