John Cena Says Hair Transplant 'Changed The Course Of My Life'

John Cena says his recent hair transplant has "completely" altered his life ... and he's ticked he didn't get the procedure done sooner.

The WWE Superstar -- who revealed back in April he had the scalp surgery after fans taunted him over his thinning hair -- went in-depth on the matter with PEOPLE this week ... and it ain't hard to tell he's loving his new look.

"It completely changed the course of my life," he said.

Cena told the magazine the operation was simple -- docs simply "move your hair, one by one, from one area to another" -- but he said it's opened up a whole new world of opportunities for him.

Specifically, he said he's actually landed more acting gigs by having a fresh, new 'do.

Cena said it takes a lot of work to maintain, explaining he's got a daily routine that includes "red-light therapy, minoxidil, vitamins, shampoo, conditioner" ... but it sounds like it's all been more than worth it.

"I hate the fact that if there wasn't so much shame around it, I'd have gotten it done 10 years ago," the 48-year-old said. "I thought I was alone, but seven or eight out of 10 [men] suffer from thinning or baldness."