Sources that can be used as evidence, such as those created or reported by someone with first-hand experience or who has made a major contribution to the development of topic or concept. True or false?

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 .