Johnson played first base in college and got reacquainted with the position while at Minute Maid Park this offseason, working out with Wallace and first base coach Bobby Meacham.
"It's going good," he said. "One of the things is just getting adjusted to the different sized glove, and you have a couple of things with pickoffs with the pitcher you have to work on. It's an easy adjustment."
Johnson lost his starting job last year to Paredes and was sent to the Minor Leagues in August, which is something he hasn't forgotten.
"I get jacked up thinking about it," he said. "Being in the big leagues is where you want to be and getting sent down is not really a good feeling. I'll just work that much harder not to let that happen again."