"It was nerve-racking, but after I got done it was like a sigh of relief," Garza said. "Eleven days inside stinks.
"It is progress and I have been making a lot of progression, so I am pretty pumped."
When asked how many pitches he threw, Garza said: "I threw just enough. That's all I can tell you.
"I threw about 15 minutes and it was a good toss, and now I will wait till the next time. Now I have to take my foot off of the gas pedal. I am the type of person that gets excited and wants to keep pushing, but this type of stuff, [my strained lat] feels great, so now I have to ease off on it. I am excited. It is fine today."
Garza is next scheduled to throw Saturday.
"Rest and see where we are at on Saturday," he said. "That's when I throw again. That is the plan."
Garza, who missed the last two months of last season with an elbow strain, said the goal is to be able to pitch pain free. He injured his left side on Feb. 17.
"The schedule isn't for Opening Day or opening week," he said. "The schedule is for when my body is ready. I am not going to rush this thing. I spent six months rehabbing, getting back from the injury last year. Time is definitely on my side right now."
Manager Dale Sveum said it's too soon to guess when Garza might be ready.
"It is way too early to evaluate," Sveum said. "We have today before we think that far down the road. If things start to go well today we are planning that he will be ready at the start of the season."
At this point, the Cubs and the 29-year-old right-hander are preaching caution.
"It is a huge deal," Garza said. "Pitching April 1 and pitching April 15, it is three or four games, but if I pitch April 1, I might reinjure it in June and be out. If I give it the other two weeks and I take my time, maybe not."
Garza said he has been able to do some conditioning work, but Thursday was the first time he threw a ball in 11 days.