Jackson said Trump urged the doctor to "answer every question" the media had before he stepped up to the podium, and he did so with gusto during an almost hour-long briefing with the media, in a remarkable show of transparency.
The President doesn't have a daily physical fitness routine, the doctor said. And Trump's penchant for Diet Coke, McDonald's, red meat and vanilla ice cream has been widely reported.
But while Jackson acknowledged he advised Trump -- who is 6 foot, 3 inches and weighs 239 pounds -- to eat better and exercise more, he said it's genetics that have kept Trump in sterling health.
"He has incredible genes, I just assume," the doctor said.
Jackson said he would work with Trump on an exercise schedule and try to enlist first lady Melania Trump to get the President to eat better.
Excellent may have been the word of the day for Jackson.
Trump's "overall health" is excellent, Jackson said, as is his "cardiac health."
"Based on his cardiac assessment, hands down, there is no question he is in the excellent range," Trump added.
Though there were things Trump could do better, he said -- on the whole -- the President is in "very, very good health."
30 for 30
Trump's cognitive health was a focus going into Friday's medical exam with Jackson and his team, and the President himself asked the doctor conduct a cognitive test.
"I have absolutely no concerns about his cognitive ability," Jackson said, noting that Trump scored at 30 out of 30 on the Montreal Cognitive Assessment test.
Trump regularly "speaks his mind," Jackson said, and the doctor "found no reason whatsoever to think that the President has any issues whatsoever with his thought process."
'Just the way God made him'
"He has incredibly good genes, and it's just the way God made him," Jackson said at one point, later joking that Trump could live a long, long time.
"I told the President that if he had a healthier diet over the last 20 years he might live to be 200 years old," Jackson said, eliciting laughter from reporters.
'Fit for duty'
Jackson, after spending four hours with Trump on Friday and evaluating his test scores, said of Trump: "absolutely he is fit for duty."
But then he took it a step further.
"I think he will remain fit for duty for the remainder of this term and even the remainder of another term if he is elected," Jackson said.