Trump said that gesticulating and speaking in front of large crowds turns very physical and that "a lot of times these rooms are very hot, like saunas, and I guess that is a form of exercise."
"I think when you're running for president, I think you have an obligation to be healthy. I just don't think you can do the work if you're not healthy," he said.
Trump talked about his medical history and noted his only trip to the hospital was when he had an appendectomy at age 11. He said that if he had been hospitalized recently, "it's going to be out there bigly."
"I feel as good today as I did when I was 30," he said, going on to compare himself to his friend Tom Brady, the New England Patriots quarterback.
"I feel the same age as him. It's crazy," the 70-year-old Trump said of 39-year-old Brady.
The topic of family came up in multiple forms during the interview. Donald Trump talked about his brother Fred Trump, who died in his 40s and struggled with alcoholism, as well as their father, Fred Trump, who died when he was 93 and had Alzheimer's disease in his later years.
"He lived to a very old age, and he was really great right up toward the end," Donald Trump said of his father.
Donald Trump's daughter Ivanka Trump made an appearance during the show and talked about her father's child care plan, as well as his role as a grandfather.
Donald Trump's appearance on "The Dr. Oz Show" was taped on Wednesday and aired today.
Trump shared the results of a recent physical exam during the taping, with Oz reading from a summary of exam results that Trump is 6 feet, 3 inches tall and weighs 236 pounds.
"I think if I had one thing, I'd like to lose weight. It's tough because of the way I live, but the one thing I would like to do is be able to drop 15, 20 pounds. It would be good," Trump said in one of the clips that was released early.
He has been pictured several times eating fast food on the campaign trail.
Hours before the show aired, his campaign released a letter from the candidate's personal doctor, stating that he "is in excellent physical health."
The campaign described the information as medical records, but it consisted of only a one-page letter from Dr. Harold Bornstein and a letter from Lenox Hill Hospital in New York City stating that Bornstein has been reappointed to its staff and has clinical privileges at the hospital.
The cholesterol, blood pressure and blood sugar levels listed in the letter were obtained during a physical exam that Trump had on Friday, Sept. 9.
His blood pressure and cholesterol are within normal levels, as is his testosterone level.
The letter said Trump had an echocardiogram and a chest X-ray but did not disclose why those tests were performed. While he has talked about his family members' alcoholism and Alzheimer's disease, the letter did not address those issues in his family health history. The letter also did not mention his current mental health.
He takes statins, which are used to lower cholesterol levels; those drugs are commonly taken by people over the age of 60.
The letter said Trump is also taking a low dose of aspirin, which can reduce the risk of having a heart attack or stroke.
His body mass index is 29.5, which is considered overweight. A person is considered obese with a BMI of 30 or more.