Rob Gronkowski's Shirtless Shots To Kick Off His 36th Birthday!

Rob Gronkowski just turned 36 on Wednesday ... and while he's been retired for a while, he still looks like he could suit up and hit the field today!!

About 3 years have passed since the tight end played in the NFL ... where he had plenty of success with four Super Bowl rings alongside his quarterback, Tom Brady.

There was no retirement bod for Gronk, though ... as he looks just like the ripped five-time Pro Bowler who set records in the NFL.

Outside of lookin' good, life has been great for Gronk -- he's gotten into business, entertainment, professional partying and television following his playing days.

And after all these years, he's still dating Sports Illustrated Swimsuit stunner Camille Kostek -- one of the magazine’s top models.