Aaron Paul ''gravitates'' towards ''darker'' roles.

The 'Need for Speed' actor - who is best known for playing troubled meth cook Jesse Pinkman in 'Breaking Bad' - is a ''happy and content'' person, so likes to challenge himself by playing characters that are so different to himself.

He said: ''I'm drawn to these roles because they make me feel emotions I'm not used to feeling.

''In everyday life, I'm very happy and content. That's why I gravitate to the dark side, for me, it's more exciting. It makes me feel like I'm doing something and not just walking through the role.''

The 26-year-old star also admitted he sometimes worries his career has peaked already because he doesn't think he'll ever get a role as good as Jesse.

He said: ''It feels [like I've peaked] sometimes. Hopefully, I'll continue to work. All I know is Jesse Pinkman is the role of a lifetime, it'll never come across my path again. 'Breaking Bad' changed my life.''

As well as boosting his career, Aaron was delighted to have found lasting friendship on 'Breaking Bad' in the form of his co-star Bryan Cranston.

He told Marie Claire magazine: ''I love that man. He is a dear friend and the biggest mentor. He's the most focused professional guy, but unbelievably immature in the best possible way. I miss laughing with him. But we'll be friends until the end of time, for sure.''