If you are going to tell people they can’t do something, or need to change a particular behaviour, offer them a better alternative.
People won’t stop doing something just because you /told them to/.
Most of us know that the motivators to change are away from pain or towards pleasure.
Instead of going with the default method of making the current option painful, make the alternative pleasurable.
Give us an incentive to change.
This allows us to make the change something we feel is worth it, rather than doing it because the was no other option.