Paul Johnson, Churchill (New York: Penguin, 2010), 122–25 (numbering added):

Winston Churchill led a full life, and few people are ever likely to equal it—its amplitude, variety, and success on so many fronts. But all can learn from it, especially in five ways. . . .

1. Always aim high. . . . He did not always meet his elevated targets, but by aiming high he always achieved something worthwhile. .  .
2. There is no substitute for hard work. . . . The balance he maintained between flat-out work and creative and restorative leisure is worth study by anyone holding a top position. . . .
3. Churchill never allowed mistakes, disaster—personal or national—accidents, illnesses, unpopularity, and criticism to get him down. His powers of recuperation, both in physical illness and in psychological responses to abject failure, were astounding. . . . He had courage, the most important of all virtues, and its companion, fortitude. . . . In a sense his whole career was an exercise of how courage can be displayed, reinforced, guarded and doled out carefully, heightened and concentrated, conveyed to others. . . .
4. Churchill wasted an extraordinarily small amount of his time and emotional energy on the meannesses of life: recrimination, shifting the blame onto others, malice, revenge seeking, dirty tricks, spreading rumors, harboring grudges, waging vendettas. Having fought hard, he washed his hands and went on to the next contest. . . . There is nothing more draining and exhausting than hatred. And malice is bad for the judgment. Churchill loved to forgive and make up. . . . Northing gave him more pleasure than to replace enmity with friendship, not least with the Germans. . . .
5. The absence of hatred left plenty of room for joy in Churchill’s life. His face could light up in the most extraordinarily attractive way as it became suffused with pleasure at an unexpected and welcome event. . . . He liked to share his joy, and give joy. It must never be forgotten that Churchill was happy with people. . . . He got on well with nearly everyone who served him or worked with him, whatever their degree. . . . He showed the people a love of jokes, and was to them a source of many. No great leader has ever laughed at, or with, more than Churchill. . . . . He liked to sing. . . . He was emotional, and wept easily. But his tears soon dried, as joy came flooding back.

You can get a good flavor of what Churchill was like by watching Into the Storm: Churchill at War (HBO, 2009). (Warning: It has some strong language.) HT: Owen Strachan.