Atticus gives Jem a definition of courage. What does Atticus mean in this quotation?

In chapter 11, Jem loses his temper after Mrs. Dubose makes several derogatory comments about his father, and he ends up destroying her camellia bush. As a punishment, Atticus forces Jem to read to Mrs. Dubose each day for two hours. After Jem has read to Mrs. Dubose for a little over a month, he notices that she is coherent throughout his entire reading sessions. Shortly after Jem stops reading to Mrs. Dubose, she ends up dying from her chronic illness. Atticus then explains to Jem that she was the most courageous person he has ever met. He tells Jem that Mrs. Dubose was addicted to morphine and knew that she did not have much longer to live. However, Mrs. Dubose wanted to break her morphine addiction before she died. Atticus then says,

I wanted you to see something about her—I wanted you to see what real courage is, instead of getting the idea that courage is a man with a gun in his hand. It’s when you know you’re licked before you begin but you begin anyway and you see it through no matter what. You rarely win, but sometimes you do (Lee, 136).

Atticus is essentially telling Jem that real courage is having the determination to face adversity for the right reasons while fully realizing that you will not win. Later on in the novel, Atticus demonstrates real courage by defending Tom Robinson in front of a prejudiced jury.