If J.J. Watt wants to flaunt his new bod, one of the greatest bodybuilders of all time is willing to help ... 7x Mr. Olympia Phil Heath tells TMZ Sports he'd have the future Hall of Famer stage ready in 3 months!
"He actually looks pretty damn good," 44-year-old Heath said, adding ... "I think he would actually do well at the amateur level."
Not too shabby a compliment coming from a man who won the Olympia seven times straight (he also finished second in 2010 and 2018).
Of course, 35-year-old Watt shocked fans earlier this week when he posted a shirtless pic looking insanely SHREDDED!
It goes without saying, J.J. -- a defensive lineman in his former profession -- was always a premium athlete, but he was listed at nearly 300 pounds. Watt's leaned up significantly.
Where's Watt strong? Weak? We asked Heath.
"I think his core looks really good. His core is a strength. His chest is a strength. In fact, his legs aren't bad," Phil told us.
"Could he use more calf development? Yes, he could definitely use more calf development. Could he use more delts? Yes. Could his arms be bigger? A lot of football fans would be like, 'Dude, his arms are sick. His arms are huge.'"
Heath continued ... "We're talking about my sport. You need to have minimum of 22-inch guns, man, especially someone being that tall. So for him to be proportionate, he's got to work that front, the side and the rear delt like crazy."
Now, it's entirely possible J.J., who made a ton of money on and off the field, doesn't want to kill himself in the gym (and at the dinner table). But, if he does, here's what Heath had to say about the fellas training together.
"I can get him ready for an amateur show in literally 12 weeks, without a doubt, without a doubt," Heath said.
"If he trained with me for 12 weeks and we made sure everything was rocking and rolling, no injuries, we do his blood work, we do all that cool stuff, we figure out his nutrition, 12 weeks, I can get him on an amateur stage. And he would actually be very pleased with how he looked. Very pleased."
So, someone order J.J. a banana hammock, some spray tan and oil ... and get Phil on the horn!
There's more with Heath ... the bodybuilding great also gave us the 411 on his brand new documentary, "Breaking Olympia: The Phil Heath Story" -- which he made with The Rock.
The doc walks viewers through his nearly unparalleled career on the stage, and in the gym, as Heath ponders a return ... as he seeks an 8th title, a feat accomplished by only Ronnie Coleman and Lee Haney.