It can be difficult going through a period of time where you feel depressed because it can become your identifier. In the sense that you wake up, you're depressed; you talk to your friends, you're complaining that you're depressed; you talk to your parents, you're unmotivated. You know what you could do to try to overcome it - although obviously there's no cure - but you start to feel like, 'what will happen to me if I feel better? Who am I when I'm happy. I'm so used to feeling like this.'

Pop music really is a love and a joy and a science [of songwriting].

If you're not inspired and you're working hard to pull inspiration from somewhere and make a song something it's not, then it's very contrived and I don't like to write music that's contrived.

If I start writing a song and you try to have a conversation with me, you're a bad person.

I wake up every day and think about what I am to other people. What I am to the people I employ, who depend on me to wake up and do my job that day and keep this career going? I think about what I am to the kids who listen to my music and all the other people involved in this project.

It doesn't matter how many private jets you take, how much money you make, how famous you get, keep putting in the hours.

Before Guadalcanal the enemy advanced at his pleasure - after Guadalcanal he retreated at ours.