What causes all the fight to go out of Da-duh?

In "The Fight," Da-duh loses her fighting spirit primarily due to the realization of her own mortality and the changing world around her. The visit from her young granddaughter, who represents modernity and a different lifestyle, highlights the stark contrast between the old ways and new realities. Da-duh's pride in her heritage is challenged as she confronts the inevitability of change, ultimately leading to her emotional and physical decline. This loss of vigor symbolizes the struggle between tradition and progress.