In comments to Chinese state media Monday, Yao sounded far from optimistic about his future and also made a rare criticism of China's national basketball program.
"If the foot injury does not heal next season, I might choose to call it quits," he said.
Rockets general manager Daryl Morey said in a statement that Yao is "currently participating in on-court basketball workouts" and is expected to be ready for the start of training camp.
Yao turns 30 in September and missed last season following foot surgery. He is set to return to the Rockets after deciding not to opt out of the final year of his five-year contract, which will pay him $17.7 million next season.
Though he has said his recovery was going well, the Rockets have signed 7-foot veteran Brad Miller to share the work at center.
"Yao Ming is working diligently on his return and has consistently received positive feedback at each of his scheduled medical checkups," Morey said.
Yao, who was in China for charity events and remains wildly popular in his country, all but ruled out playing in the 2012 London Olympics.
"The chance is very small," the 7-6 center was quoted as saying by the official Xinhua News Agency. "The foot injury will not allow me to play so many games anymore. Like I said before, I will quit the national team and the sport one day. It's what happens to every athlete."
Without Yao, the national team has played lackluster ball, including an embarrassing home loss to Iran in the final of the Asian Championship last year. Yao attributed the poor showings to China's focus on the 2008 Beijing Olympics and neglect of development teams and the country's professional league.
"We are paying for what we didn't do leading up to 2008. We skipped the development of a reserve team and the CBA league and focused only on the national team and the Olympics. It's like you are killing the goose that lays the golden egg," he said. "I'm 30. As an athlete, I am not the future of China basketball anymore."
Information from The Associated Press was used in this report.