Lilly -- the Cubs' lone All-Star in 2009, when he went 12-9 with a 3.10 ERA in 27 starts -- worked out at Northwestern University with pitching coach Larry Rothschild and some of his teammates. They are in town to take part in the 25th Cubs Convention, which opened Friday at the Chicago Hilton.
"It was a nice, moderate day of catch," Lilly said. "I played catch with [prospect] Andrew Cashner. His arm definitely looks healthier than mine."
Lilly had the procedure performed on Nov. 3 and was expected to miss the first month of the 2010 regular season. He said the time off has made him appreciate the game even more.
"I cherish this dream I had as a little kid to play baseball," Lilly said. "I want to do it, and when you have something come up like shoulder surgery, you're in a situation where you feel like if you don't do everything you can, it could be taken away from you. I'm not ready for that.
"I'm going to do everything that's in my control to not allow that to happen."
Lilly hasn't extended his throwing too much.
"It feels good to move it around," Lilly said. "It's a catch-22. If I don't [move it], it gets stiffer.
"There have been no setbacks and no reason to slow down."
The Cubs head into 2010 with Carlos Zambrano, Ryan Dempster and Randy Wells secure in their rotation, with Carlos Silva, Jeff Samardzija, Sean Marshall and Tom Gorzelanny among the candidates for the other two spots.
Lilly isn't sure how he'll handle being sidelined for that first month of games.
"I know I'll get bored," Lilly said.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.