The singer-and-actor insists he is very shy and claims he never fitted in when he was younger because he wasn't interested in sport.
He said: “I'm actually quite shy and prefer to be on my own. I'm not very talkative either.
“I've always been reserved. In my hometown you only used to be someone if you played football. But all I was interested in was music, so I was an outsider. The others didn't think I was cool.”
Justin – who is in a relationship with Jessica Biel and has previously dated Cameron Diaz and Britney Spears – claimed looks don't matter to him and he looks for comfort and trust in the women he dates.
He explained: “Looks are secondary. I fall in love with a girl because she might have the right attitude towards life. I have to feel comfortable with her and trust her.”
The 29-year-old star also admitted he had experienced a broken heart in the past.
He told Germany's IN magazine: “I haven't always been very lucky. But that's normal. And when you love someone you have to be able to endure pain.”