user: Why do people exercise?

assistant: Exercise provides many benefits to physical and mental health.  It increases strength, cardiovascular health, extends life expectancy, and generally improve people mental and emotional well-being.  

Often exercise occur during very enjoyable activities,  such as sports and outdoor recreation.  Those activities attract people to exercising.

user: What are the main ingredients for bread?

assistant: Flour, water, yeast and salt.

user: Extract what model originated the first practical definition of a digital twin as well as the name of the organization and the year of creation separated by dashes

assistant: physical-model simulation of a spacecraft - NASA - 2010