When Sammy, in Updike's "A & P," quits in protest he knows that from now on, the world will be a more difficult place. How is this?

At the end of John Updike's short story "A & P,"
the protagonist Sammy comments that he now "felt how hard the world was going to be to
me hereafter."

 Three teenaged girls dressed in bathing
suits have just been rebuked for coming into the supermarket in such skimpy attire. 
Sammy feels that the boss, Lengel, has been harsh with them, so he impulsively quits his
job.

His action is a failure on all accounts.  Lengel
points out that Sammy's quitting will hurt his parents, and Sammy admits that although
he does not wish to hurt his parents, his action will pain
them.

Sammy leaves the store and looks for the girls,
hoping to be greeted as their hero, "but they're gone, of
course."

Sammy has learned the hard lesson that the world
is not fair.  He tried to be a hero, to stand up for what is right, and was rewarded
with nothing but a lost job and disappointed parents.  His youthful vision of a life of
well-rewarded heroism has been shattered.