President Trump spent more than two hours at Walter Reed National Medical Center on Saturday, undergoing what the White House said were medical tests as part of his annual physical.

The appointment -- which followed a previous exam in February -- didn't appear on the president's public schedule, as was the case for his physicals last year and this year. White House press secretary Stephanie Grisham told Fox News' "Justice with Judge Jeanine" on Saturday night that Trump had decided to "kind of get a headstart with some routine checkups."

"We've got a really busy year ahead, as you can imagine," said Grisham, referring to the president's 2020 reelection campaign. " ... It was very routine. We had a down day today and so he made the decision to head there."

Grisham added that the president "is as healthy as can be ... He's got more energy than anybody in the White House. That man works from 6 a.m. until very, very late at night. He's doing just fine."

The president later tweeted about his visit to Walter Reed, adding that he visited with the family of a patient who was undergoing major surgery.

"Everthing very good (great!)," the president wrote. Will complete next year."

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In a statement earlier Saturday, Grisham said Trump, 73, had “a quick exam and labs” and assured that he remains in good health.

“The President remains healthy and energetic without complaints, as demonstrated by his repeated vigorous rally performances in front of thousands of Americans several times a week,” she said.

Saturday's visit was Trump's ninth trip to Walter Reed since taking office in January 2017.

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Results from Trump's last physical nine months ago revealed he had gained six pounds since taking office. At 243 pounds and 6 feet, 3 inches tall with a Body Mass Index rating of 30.4, the president passed the official threshold for being considered obese. Obesity, a common weight condition that affects 40 percent of Americans, can increase the risk of heart disease, diabetes, stroke and some forms of cancer.

Trump doesn't drink alcohol or smoke but has a hearty appetite for fast food, steaks and desserts. His primary form of exercise is golf.

The Associated Press contributed to this report.