Need and Interest
Many of the people who exercise the most outside of the gym are the ones you'll find in the gym.
People who are very well-read are more likely to go to bookstores and libraries than those who are not.
Individuals who really need to see doctors may be among the most reluctant to schedule a medical appointment or exam.
When marketing, it is important to recognize that need does not always produce interest if only because one person's requirement is another's mere option..
Inertia is a powerful force. So is self-destructiveness.