In a hugely revealing interview with USA Today, members of U2 opened up about what keeps them motivated and what drives them to keep performing and touring with such innovation and passion.

Speaking to Enda Gundersen, The Edge, aka Dave Evans, channeled his Robert Frost by saying the band’s longevity and success was because they chose the road less traveled by.

"It's important to challenge ourselves creatively and not take the soft option," said the cap-wearing one.

"That's so ingrained in the band that we'll continue to grow and develop. We owe it to ourselves and our fans to take it further out there and break new ground."

For Adam Clayton, oft regarded as the most enigmatic member of the band, it is the importance of adapting with the times and doing it out of choice, and not necessity.

"I want our music to be relevant," he told USA Today.

"They don't have to be big-selling records. Hit records are absolutely the business you should be in if you're in popular music, and we'll always strive for that. But it's a big privilege to be able to do what you love to do. You haven't lost control of it. You're not doing it to cover bad debts or bad deals. And it's great working outdoors."

As for Larry Mullen Jr., the former Artane Boys Band member feels that the foursome treaded water early in their career and now they have to match their inspiration with the proper amount of perspiration.

"It's an Irish Catholic guilt thing," says arguably the most handsome member of the quartet.

"We should have been better and worked harder. In the '80s, we were green. We lurched. We were successful despite ourselves. Now there's a sense that we've got more to do, that we can continue to push it, to take risks. Complacency is not something we're good at or comfortable with."