The Madrid-born artist - who debuted in 1995 with a self-titled album and releases the greatest hits compilation "95/08" in March - said dissatisfaction with his own work is what drives him to continue performing and recording.
"When I listen to my music I think it can still continue to evolve," he said. "After a couple of months go by, I think I could write a better song."
Iglesias said he is striving to make the perfect record - "One you listen to 10, 15, 20 years from now and say, 'Oh! I wouldn't change a thing."'
And until Iglesias makes that album, it seems his plans could change.
"I want to retire in the next 15 years," Iglesias said. "But that's what I say now. Who knows if I'll have the courage to do it when the day comes."