How can watching be non-doing?

In Vipassana meditation ,it is emphasized that one should not force the mind to concentrate on certain object or force anything to happen in particular.Its kind of letting things unfold and just watching them as they unfold .But for an untrained mind isn't watching by itself a kind of doing and if it shouldn't be a doing and is the natural state of restful alertness ,how can it be initiated without the mind feeling forced to do it.If one is driven by conditioning in a non doing state. Ardency as I understand is an important aspect of the practice ,but doing it on the razor's edge of not falling into forcing the mind,is tricky.What is the best way to initiate it so it becomes right mindfulness?.