Final answer:
Good health in middle adulthood is positively influenced by a sense of control and active engagement in physical and mental activities, aiding in better health outcomes.
Step-by-step explanation:
True, good health in middle adulthood is, in part, determined by having a strong sense of mastery and control over their lives and actively engaging in challenging physical and mental activities.
The assertion aligns with studies that show how higher levels of perceived control can lead to better health management and reduced risk of physical health problems.
Individuals who view their health as controllable are more likely to adopt healthier behaviors and maintain an active lifestyle, which can mitigate physical declines associated with aging.