Zac Efron: I'm finally happy

Zac Efron has admitted it "took a lot of work" to feel comfortable in his own skin.

The That Awkward Moment actor reportedly had two stints in rehab last year for problems related to drink and drugs.

During an appearance on Running Wild With Bear Grylls, the 26-year-old opened up about what his life was like in the time before he decided to get help.

"It was getting to the point where I was caring less for the work and waiting more for the weekend, where I couldn't wait to go out and sort of let loose and have fun," he admitted to the British adventurer. "But when Monday and Tuesday were difficult to get through, then I was like, 'Ah, this is bad.'"

However, the 17 Again star knows how to handle his fame much better now. He is determined to make sure he doesn't need outside influences to be in a good place from now on.

"I just really never again want to have to take anything from the outside into me to feel good about my outside, to be comfortable in my present skin," he explained, before adding, "And that takes a lot of work. It's just meditation, and stopping and slowing down your brain."

The star had plenty of time to reflect on things during his trip with Bear, 40. As well as jumping from a helicopter, rappelling down a 150 foot waterfall while shirtless, and crawling across a rope stretched terrifyingly high between two cliffs in the Catskill Mountains, Zac also had to eat worms after they were unable to find another food source during their two-day challenge. But despite their trials, The Lucky One star found the whole experience liberating.

"I've never felt really this alive," he said. "I've never done a movie this challenging - I've never been through anything quite like this. I'm pretty stoked."