Right-hander Lucas Giolito “is always going to be a little kid at heart,” James Shields said. “Aren’t we all?” Baseball is a kid’s game and always will be, and even 36-year-olds such as Shields don’t always act their age in a clubhouse or around the ballpark. But there’s a time to be serious, and it’s apparent to Shields that Giolito, 23, knows when. “He’s definitely well beyond his years,’’ said Shields, owner of 2,080 career strikeouts and nine consecutive seasons with 200-plus innings pitched. “He has a great attitude every day and works hard. He comes to the park with a purpose, and he knows himself.’’ Giolito, who made his first 2018 Cactus League appearance Wednesday with two so-so innings in the White Sox’ 5-4 victory against the Texas Rangers, struggled last spring but got it together working through 24 starts at Class AAA Charlotte. Then he posted a tidy 2.38 ERA in seven starts with the Sox in August and September. “The thing I saw last year was the in-game adjustments he made hitter by hitter, which is very difficult for a young guy in the big leagues,’’ Shields said. “You want to pitch to your strength, but you realize these are big-league hitters, and your strength might not work to that particular hitter.’’ Giolito is taking notes.