Why doesn't being the granddaughter of slaves cause feelings of depression in Zora?

For Hurston, slavery was the price that she "paid for civilization", for opportunity, and the freedom to be whatever she wanted to be.

Someone is always at my elbow reminding me that I am the granddaughter of slaves. It fails to register depression with me. Slavery is sixty years in the past. The operation was successful and the patient is doing well, thank you. The terrible struggle that made me an American out of a potential slave said "On the line!" The Reconstruction said "Get set!" and the generation before said "Go!" I am off to a flying start and I must not halt in the stretch to look behind and weep. Slavery is the price I paid for civilization, and the choice was not with me. It is a bully adventure and worth all that I have paid through my ancestors for it. No one on earth ever had a greater chance for glory. The world to be won and nothing to be lost. It is thrilling to think—to know that for any act of mine, I shall get twice as much praise or twice as much blame. It is quite exciting to hold the center of the national stage, with the spectators not knowing whether to laugh or to weep.