Why Trump is right to worry about that glass of water

He might well be revealing his own insecurities. But he’s also right about one important thing: just how damaging such a picture of weakness can be. It may sound trivial, and it’s often unfair, but when a modern president, or even a candidate, exhibits physical weakness, it comes with a political cost.

It helped sink President Gerald Ford—perhaps the most athletic of our recent presidents; football star at the University of Michigan, skilled skier. But a couple of stumbles down the steps of Air Force One, a tumble on the ski slopes, and the relentless mockery of Chevy Chase on “Saturday Night Live” cemented a new image of Ford that stuck: A fumbling character barely able to put one foot in front of the other.

After him came President Jimmy Carter, who, in the midst of declining polls and a looming primary challenge from Ted Kennedy, sought to demonstrate his energy by entering a challenging six-mile race in the Catoctin Mountains in mid-September, 1979. Midway through the race, he all but collapsed into the arms of a Secret Service agent; pictures of the open-mouthed, utterly drained Carter became the symbol of an exhausted presidency.

Or think back to George H.W. Bush, whose appetite for recreation was on frequent display on golf courses, tennis courts and the water. But on January 8, 1992, in the middle of a state dinner in Japan, was struck by a flu bug and vomited.