In the mundane world, we are always attached to phenomena created by the mind. We keep relying on the phenomena. These become our habitual thoughts, our habits. So in zen Buddhism, to be enlightened you have to be enlightened to this formless mind. But for gradual practice, we have to let go of attachments to all phenomena that we have cultivated for a long long time. Once you completely destroy all patterns you have built then you can be enlightened to this formless mind. You have to be enlightened to the mind first to really truly practice.
In the zen hall our purpose is to become enlightened to this formless mind; to engage this formless mind. Mundane people have too much material attachments. It is difficult to let go of these, so if we just say enlightenment, it is not useful for mundane people.
True practice is based on gradual daily practice. Lose attachments day by day. Attachments are just like dust, every day there are new dust that accumulate.
When we remain calm in mind, no matter what kind of problems we face in life, the mind is always calm. That is a way of practice.