The Swede, at 39, is Serie A's leading goalscorer.
“Zlatan is in such good shape, sometimes he continues to do press-ups when I am sitting on him. And you know I am not light," Raiola told De Volkskrant.
“He can play on until he's 50 years old, but he only wants to play at the top level. He's certainly at the top level now, as he resuscitated Milan and is now 90 per cent of that team.
“He inspires people not by what he says, but what he does. There's also a little glint in his eye and a wink in everything he says to the media, the truth is he's self-critical to an unimaginable degree. Failure just drives him crazy.
“Where were PSG before Ibrahimovic? Where were Milan? He sets the standards that clubs then benefit from for years to come. He passes on these lessons to the next generation and that's why he should continue for as long as possible."