The problem today may be that the job is too small to keep one person busy. Every president within my memory has, like Reagan, showed signs of having too many idle hours. I will delicately pass by the Kennedy and Clinton years. To see the point, all you have to do is think about Richard Nixon sitting in the White House micromanaging his paranoia or Jimmy Carter whacking away at an attack rabbit. That is how guys act when they have nothing better to do.
Presidents travel, meet interesting people, and get to inspect cool things like aircraft carriers.
I envied Gerald Ford his ski trips and I envy Bill Clinton his beach walks. One approach is to rewrite the job description. The incentive for a good performance would be a book contract and a significant building, airport, or monument named in the president's honor. A poor performance would carry with it a biography by Kitty Kelly and the ex-president's name on IRS headquarters. Two other business world approaches to the presidency problem would require changing how we think about who should be president.