Justin Bieber says he “can’t believe” how strong his mom is.

The 18-year-old pop sensation was asked about his mother’s new book Nowhere but Up: The Story of Justin Bieber's Mom, Pattie Mallette in an interview with ET. In the tome, Pattie reveals her experiences with sexual abuse and depression before the birth of her son.

Justin is in awe of how brave his mom has been throughout her life and hopes her story will help others.

"My mom went through a lot growing up, and I feel like it's going to help a lot of young girls who went through a similar story," he explained. "She didn't tell me any of it until I was old enough. I was like, 'Wow, I can't believe you stayed so strong through me being young. It's great.'"

Justin also spoke about his plans for the future. He is currently on the North America leg of his Believe tour, and although he is still committed to music he is also eager to land more acting roles.

The star – who previously appeared in CSI – revealed he has several projects in the pipeline and would love to test out his comedy skills.

"I hope to [go] further in acting. I have a few offers for different scripts after my tour's done, so I'm pretty excited about that,” he added. “And I just want to figure out roles that are going to be good for me. I want to do some comedy stuff ... I want to do some action stuff..."

Justin’s hectic schedule appears to be taking a toll on his health.

The singer was sick on stage in Arizona during the first concert of his tour.

In a clip posted on TMZ, Justin is seen dancing and singing before he turns his back to the audience and vomits.

He then ran to the side of the stage while his backing dancers continued with the show.

Justin promised to “slow thing down” but was forced to leave the stage again due to illness.

He later took to his Twitter account to assure fans he was on the mend.

"Great show. Getting better for tomorrow's show!!!! Love u (sic)" he wrote.