AceShowbiz -

Zac Efron opens up about his substance abuse. While sitting by a campfire with the host of NBC's "Running Wild with Bear Grylls" during a recent episode, the hunky actor who started out his career as a Disney star said being young and famous, he had a hard time dealing with the media pressure.

"The challenging part was never the work. That was never it," the "High School Musical" alum, now 26, explained. "It was sort of the in-between work - the social aspects outside of it. I mean, everywhere you go to a certain extent, there is press in some form."

"Whether you're going to an event where you're supposed to be out...there will be press there, if you're leaving your house to go to the grocery store, there will be press there. It can be everywhere and it can be confusing," he added. "You spend a lot of time in your house, going crazy and pretty soon you need a social lubricant. And once I needed that, it became to go anywhere."

"It was getting to the point where I was caring less about the work and waiting more for the weekend, you know what I mean, when I couldn't wait to go out and sort of let loose and have fun. But then when Monday and Tuesday were difficult to get through, I was like, 'Oh this is bad,' " he went on.

"I just really want to never again have to take anything from the outside into me to feel good about my outside, to be comfortable in my present skin."