The hugely successful boy band have shared a closer bond since their reunion in 2006 and the singer admitted it can tough adjusting to life outside the ''familiar'' close-knit group.
He said: ''Being able to sit in a room together and talk and laugh is our reward. And it's familiar - you know what it is, which sometimes means that you can come out of that room and go, 'Oh my God, what am I doing now?'
''I can only speak for myself, but I think that half the time, trying to work out who you are when you're not in that situation is the difficult part. I've spent more of my life in that band than not.''
The 41-year-old star revealed his band mates have heard his new solo album 'The Art of Doing Nothing' - and they've been ''enthusiastic'' enough to help him realising he can ''stand on'' his own.
He told The Sunday Times newspaper's Culture magazine: ''They've been really positive and enthusiastic about the album. When you get that, you go, 'Oh, the lads like it - that's OK then'.
''I really do have to remember that I can stand on my own, and puff my chest out. I do get panicky sometimes, but then I'll listen to the record and think, 'Phew, it's actually all right'.
''We joke about it, but the album is a little bit like a self-help exercise. I remind myself to listen to what I'm saying on the album, and that makes me feel better about it.''