In No Exit, main character Joseph Garcin believes he has chosen courage as his value system. By calling himself a courageous man, dreaming of courageous acts, and aspiring to be courageous, Garcin believes he has proven himself to be brave. But Sartre maintains that value systems exist only after we choose them, and that such a choice is made through action, not through wishful thinking. Because Garcin acts in a cowardly manner, he is a coward, regardless of the value system he claims to have chosen.
Garcin’s least courageous act comes in hell, not on earth.