The Cubs surprised four young patients, their best friends and family members with a once-in-a-lifetime trip Wednesday.

The patients, who all are receiving treatment at Advocate Children’s Hospital for various forms of cancer and heart health issues, were invited to join the Cubs next week at spring training in Mesa, Ariz.

None of the young patients — ranging in age from 12 to 17 — had any clue why they were asked to meet at the American Airlines Conference Center near Wrigley Field. That was until the lights dimmed and Cubs outfielder Albert Almora Jr. appeared on the screen to announce they all were getting a free trip to spring training.

Zachary Lum, a 17-year-old battling cancer who is also an avid Cubs fan, said he knew something was up earlier this week when his parents told him they were going on a trip to Milwaukee.

“She tried to trick me,” Lum joked while pointing at his mother, Donna Potts, after the video. “But I was like yeah, OK, it’s definitely spring training because it’s in February.”

Although Potts knew that the Cubs were going to officially invite Lum to spring training Wednesday, she was still overcome with emotion seeing Lum’s smile, especially after his arduous journey this past year.

Lum was diagnosed with Osteosarcoma, a type of bone cancer, in 2017 and he had his right leg amputated shortly after doctors found a tumor below his knee.

“It’s overwhelming,” Potts said. “It’s been a wild ride with all the treatments and everything over the last year and I can’t explain it. It’s a glimmer of normalcy.

“I love his smile, and to see him smile throughout all of this, it warms my heart.”

This is the second time the Cubs have invited kids battling adversity to spring training. Last year, the Cubs helped coordinate free trips for nine patients. Advocate Health marketing coordinator Cristina Enea said this trip creates a special bond between the families.

The invitees will enjoy personal time with Cubs players and coaches, plus a variety of behind-the-scenes experiences. They’ll also receive swag bags, play catch with players and participate in team stretches.

The group will depart Chicago on Monday and spend three days in Arizona before returning Feb. 21.

Lum said he’s excited about this opportunity before he finishes his last two rounds of chemotherapy.

“It’s not necessarily an escape,” Lum said. “I see it more of an opportunity.

“Yes, having cancer sucks, but also being out with my family and friends, it’s going to be great. And seeing the team I love the most play, it’s awesome.”