"There is no significant damage that would require surgery, basically. So obviously that's good news," Lilly said.
Lilly was cleared to go back to work on Friday and was throwing long toss during a morning workout for pitchers and catchers in Mesa, Ariz.
"I think I'm going to have to make a few adjustments to my conditioning, not pound on it too much, which will be tough," Lilly added. "I'm still expecting to try to catch up with the rest of the guys."
Manager Lou Piniella said Lilly may have to cut back on all the running he does to stay in shape and switch to an exercise bicycle.
"We are just going to monitor him and see how he is," said Piniella, whose team was ravaged by injuries last season. "It would have been a lot worse."
Lilly is rehabbing from the left shoulder surgery he had in November. The left-hander also had meniscus surgery on his left knee in August.
Lilly threw off flat ground Thursday for the first time since undergoing surgery on his throwing shoulder in November. He threw 25 pitches.
Lilly went 12-9 with a 3.10 ERA last season for the Cubs.
Bruce Levine covers baseball for ESPNChicago.com. Information from The Associated Press was used in this report.