"I couldn't do anything to get my heart rate up to where my lungs would expand because your ribcage is affected by that," Peavy said. "Not doing anything for a three-week period is not ideal in the middle of the season to try to come back and be full strength.
"So the biggest thing is trying to come up with a game plan to get your legs back under you, get your cardio back where it needs to be and arm. Make sure you mechanically stay the same. A lot goes into it. We'll do all we can do."
Peavy remains unsure about how this injury came about, offering up that it was a gradual thing and that the problem was slightly exacerbated by him pitching against Seattle on June 4. In a strange twist, Peavy told the media that he thought he had a broken rib last year in Detroit, but it turned out to be a false alarm brought about by an old X-ray machine.
If the rest of Peavy's rehab work progresses as smoothly as Wednesday, he believes a return right after the All-Star break is possible.
"We play catch through the end of the week," Peavy said. "Next week I'm going to try to get on a mound and see how that goes a few times. Get on a mound a few times pain-free, and I want to pitch. I'm sure they are going to make me go on rehab starts which is OK.
"I'll try to keep those to one," added a smiling Peavy. "We'll see how that goes. It's obviously for the front office to come up with. But I hope that timeline we just talked about is right around the All-Star break and I would love for that to be a reality."
Patience holds as a key for Peavy, even if he's not blessed with an abundance of that trait.
"I'm getting older. I am getting wiser," Peavy said. "I'm not going to run out there anymore like I tried to do there in Seattle, tried to tough through. At the end of the day, you aren't helping anybody by going out there."
Scott Merkin is a reporter for MLB.com. Read his blog, Merk's Works, and follow him on Twitter @scottmerkin. This story was not subject to the approval of Major League Baseball or its clubs.