What do you think was the main reason why the Allied Powers (Britain, France, Russia- who leaves in the middle, & The USA- who enters in the middle) won WWI?

In a study, people were asked to imagine simple occasions that made them happy and to remember events that made them feel proud about themselves. it was observed that the subjects developed an increasingly positive attitude. these changes are known to be healthy, leading to greater physical activity and reducing unhealthy habits. based on this excerpt, we can conclude that a positive attitude .