A good president needs a big comfort zone. He should be able to treat enemies as opportunities, appear authentic in joy and grief, stay cool under the hot lights.
A president cant go to every memorial service.
In 2001, President George W. Bush was condemned for politicizing science with his decision to limit federal funding for stem-cell research; in 2009 President Obama was praised for reversing it, even though his decision was arguably just as political.
Lyndon Johnson realized he really was President, that his identity had changed by President Kennedy's shocking death, when aides who had been like family to him minutes before, stood in his presence on Air Force One.
Eisenhower advocated a variety of strong actions which he had never taken when he was president. Maybe this was just the pattern of former presidents; maybe it reflected how much the circumstances had changed on the ground.
Americas presidents tend to die young. Maybe it is in the nature of the men who reach such heights, or of the job once they attain it.