The 17-year-old model said drugs scare him.
"Drugs and stuff scare me. I'm not just saying that. I have a thing where if I'm not in control, I feel the whole world is about to collapse. So it's just not worth it," Mendes said.
The "Stitches" star also has a level head about success and does not let fame over power him.
"That's the big thing that has hit me lately. It's all come together, but it's hard for me to just say, 'Wow, this is amazing - I'm famous. I'm living the dream!' I sit there and think, I'm scared - this can go away tomorrow.