Two of the core insights of Buddhism is impermanence and no “I”, and the two seems intimately connected.
When we more fully realize impermanence – fully allow it to sink in and be brought into awareness – then we have a chance to notice that which is not changing, which is ourselves as formless awareness, the Witness, or – going further – the ground, emptiness dancing, what is with no “I”.
And it is only when we find ourselves as formless awareness – or the ground – that we can fully allow impermanence into awareness. Otherwise, if there is an “I” there and we have not yet awakened to the ground, it is just too difficult to fully acknowledge, it seems to threathen our very existence as this “I” – placed on something that itself is impermanent.
So to fully bring impermanence – of the whole world of form and phenomena – into awareness, we need to have fully awakened to/as the ground, to emptiness dancing, to no “I” anywhere.
Contemplating impermanence then, or more simply just fully bring whatever the impermanence which is inevitably here in our lives into awareness – including all the fears and other reactions it brings up, may be one of the faster ways to a realization of the ground and no “I”.
And more generally, we can allow whatever is experienced more fully into awareness. Experiences always change, and being with this change allows us to more easily notice that which is not changing. First, ourselves as the Witness, as pure awareness, stainless, timeless. Then, what is – often the same content as before – but with no “I” anywhere, with an immediate realization of it all as emptiness dancing.