Boyzone were in a "dark place" during their last tour.
The Irish boy band struggled to cope with the loss of bandmate Stephen Gately in 2009, and band leader Ronan Keating admits he wishes they hadn't embarked on their 2011 'Brother' tour, which commemorated the late singer.
He said: "It was a weird time, that 'Brother' tour in 2011. I wish we hadn't done it, to be honest. It was my most emotional and the most difficult thing I've ever done in terms of work."
Fellow singer Keith Duffy added: "It was a painful tour. By the time we came out the other end of it, we were all in a really dark place.
"I was drinking way too much just to numb the pain. By the time it was over it had been going on for so long, and drinking to that extent, for that length of time, left me in a really bad way.
"It took me a long time to get out of it. I had to go to bereavement counselling after that. It really helped to sort my head out. When you say your problems out loud, it all of a sudden becomes easier to deal with. Keeping them locked in doesn't help."
The 'No Matter What' hitmakers - also consisting of Shane Lynch and Mikey Graham - are set to celebrate their 20th anniversary in music with a new album, 'BZ20', and they plan to make the most of their latest comeback.
Mikey enthused to The Sun newspaper: "We're not scared any more, we're not scared to say the wrong thing. We're grown men and we understand each other and the business we're in.
"Not in our wildest dreams did we ever envisage celebrating 20 years and we don't take it for granted."