The England international, who turned 33 in May, will mark the 15th anniversary of his Liverpool debut tomorrow.
"The fact that he's still so fit and runs as many miles as he does during games shows you how well he has looked after himself," Mignolet told the Liverpool Echo.
"It's not only what he does on the pitch but the way he is off it as well. He's a gentleman. He has achieved so much in his career and I wish him many more years at Liverpool.
"Look at the quality he produced against Everton – he's been doing that for 15 years and I'm he will continue in that way for years to come."
Gerrard is expected to feature in Liverpool's match against Hull City on Sunday.