"Last year going into spring training, I was struggling," the pitcher said Wednesday. "I was trying to convince myself I was better than I was, but I was doing a poor job of it, I think."
Wainwright had minor elbow surgery after the 2017 season and was just 2-4 with a 4.46 ERA last year, appearing in only eight regular-season games. His average fastball velocity dropped 1 mph to 89.75 mph, down from 92 mph in 2013, when he went 19-9 and helped the Cardinals reach the World Series.
"I'm excited to play baseball again without having to flinch every time I throw a ball," Wainwright said.
Wainwright finished second or third in National League Cy Young Award voting four times in six seasons through 2014. But he is 29-19 since then, averaging 18 starts per year.
Coming off a $97.5 million, five-year contract that paid him $19.5 million last season, the 37-year-old right-hander agreed to a $2 million, one-year contract that allows him to earn $8 million in performance bonuses as a starting pitcher, $3 million for relief appearances and $4 million more for games finished.
Wainwright is scheduled to throw his first bullpen session on Thursday.
"When I look at our lineup, and I look at our bullpen and I look at our starting rotation, I don't see many holes," Wainwright said.
Cardinals All-Star catcher Yadier Molina loosened his arm and monitored throwing sessions but never put on his shinguards. Molina is recovering from left knee surgery in December and isn't expected to catch bullpen sessions before the start of exhibition games.
"He's able to do everything, it's just a matter of -- listen, it's Day 1 of pitchers and catchers," St. Louis manager Mike Shildt said of Molina. "We don't feel like we need to push him to do anything."