Buddhism is a path – a skillful means – that can help people liberate themselves. It is not the only path, though. Zen is also a means to achieve enlightenment. If we present it as the only means, we are not enlightened to the truth.
Understand the concept of purification, and your mind will open. If you insist that Zen practice is the only way, your mind will close. If your mind is closed, its path of understanding becomes narrower and narrower, which can touch a narrow field. However, if you open the mind, the field will expand.
Simply remember that the practice should always be there regardless of what you do. The result of your practice should be readily apparent to others.
If you can genuinely achieve positive change, you can also demonstrate the potential for good to others. Changing your eating habits, improving your temper or eliminating negative habits such as smoking are positive adjustments. People will appreciate the progress you have made.