TORONTO -- Vladimir Guerrero Jr. was determined not to show up to another spring training carrying more weight than he wanted.

Embarrassed and apologetic after arriving out of shape at summer camp in 2020, the Toronto Blue Jays slugger worked aggressively on his conditioning this offseason, and said he has lost 42 pounds since last July.

"I came to spring training out of shape for a couple of years," Guerrero said through a translator Wednesday from Blue Jays camp in Dunedin, Florida. "One day at my house in the Dominican I just sat down and thought about all this. I decided right then that I was going to get ready, I was going to prepare myself, I was going to work very hard for this year. I did, because my main focus is just to be ready and help the team win."

A slimmer-looking Guerrero said he now feels stronger, quicker, and more resilient.

"I worked very hard on my legs because I really wanted to trust my legs," he said. "Before, I wasn't getting to ground balls. Sometimes at the plate I couldn't stay back enough on the ball.

"I feel quicker in all aspects of my game right now," Guerrero added. "Running the bases I feel great. Before I would feel a lot of fatigue after taking ground balls. Now I can take 50, 60 ground balls and I'm feeling good."

Manager Charlie Montoyo praised Guerrero for his transformation.

"He met his goals," Montoyo said. "He had a great offseason. All his work, it paid off. He looks really good."

Guerrero, who turns 22 in March, hit .272 with 15 home runs and 69 RBI as a rookie in 2019. However, he hit his final home run on Aug. 16 and looked tired down the stretch, eventually missing time with a sore right knee.

Guerrero dropped weight before spring training in 2020, but gained it back after the COVID-19 pandemic shut down baseball for several months. Last November, Guerrero told a Dominican newspaper he had apologized to his Blue Jays teammates after showing up overweight for summer camp when baseball returned in July.

"For the last couple of years, they knew I was coming here out of shape," Guerrero said Wednesday. "I didn't prepare myself very well and I felt like at that moment that my teammates needed an apology from me."

After switching from third base to first base in 2020, Guerrero hit .262 with nine homers and 33 RBI, playing in all 60 games of the pandemic-shortened season.

While working out this winter, both in the Dominican Republic and at Toronto's Florida complex, Guerrero said he was motivated by his teammates - from current ones in Bo Bichette, Cavan Biggio, and Teoscar Hernandez, but also new ones signed in free agency, including outfielder George Springer and infielder Marcus Semien.

"We're going to have a great season with those guys in our team," Guerrero said.

Guerrero has been vocal about wanting a shot to improve defensively at third base, where he made a team-high 17 errors in 96 games in 2019. He said the Blue Jays told him to expect games at both first and third base this season.

Montoyo said he and general manager Ross Atkins spoke to Guerrero on Wednesday and told him to concentrate his efforts on improving at first base.

"My first baseman is Vlad Guerrero and my third baseman is Biggio," Montoyo said. "But if we're facing a tough lefty or something and I'm looking to give Biggio a day off, then Vladdy could play third.

"Our main message was 'Become a Gold Glove first baseman and then we'll move you to third, see how it goes.'"