I think it's fair to say that Billie Joe, the frontman of punk rock band Green Day is ageing very well, especially considering the rock'n'roll lifestyle he's been living for the past couple of decades.
Billie Joe Armstrong looking pretty hot for his age
The talismanic singer was born in 1972 and started singing and playing guitar with Green Day in 1987 - that's a long time for a band to keep going!
There are many examples of groups that struggle to stay together for 5 or 6 years, so to go over 2 decades without splitting up is a testimony to how close the band are.
Another thing that sets Green Day apart is, as you mentioned, the youthful looks of its main man. In 1994, this is what Billie Joe looked like:
Now imagine him with black hair and less stickers on his Fender Stratocaster (from what I've seen of him lately, he's more of a Gibson single-cut Les Paul kind of guy).
What you'd have is a Billie Joe that looks alarmingly like the one we know from 2013:
Considering the reported substance abuse, constant touring, and even a stint in rehab - I think it's amazing that Billy Joe looks the way he does.
The only feasible explanation is that he knows this guy: