Example:
For all the right reasons, a person wants to start going to the gym but their parents can't be easily convinced since it costs a pretty penny and doesn't seem to figure out why's it necessary for their son/daughter to go to the gym right away. A person that's in terrible need to do it starts persuading parents into realizing that workouts are good for the overall wellbeing of mind and body and will be quite useful for better concentration in school, increasing energy, reducing the risk of chronic disease and is good for health in general.
Eventually, the parents will see all the benefits of it and will be easily persuaded because they'd do all for the wellbeing of their child.
