In the normal everyday mode of cognition, rather than apprehending the impermanent flux of existence, we freeze-frame, fixate and conceptualize the flow. We see manifestation as comprising of discrete self-existing things.
Just below this fixation mode is what might be called the process mode of cognition. When discursive thought eases and the tendency to fixate, conceptualize and abstract abates, there is a felt-sense of the happening of existence. This reflects how manifestation truly is. Existence is a happening.
This mode of perception is not something that is difficult to access - it's already how experience presents itself but is (or can be) overlaid with the narrative and fixations of thought. A baby operates from this process mode. A baby has no conception of things - there is just the fluid sweep of sensation and process. There is no narrative of the past - no memory-self - things simply are as they happen - outside of time and conceptualization. Process or flow is primary - before naming and fixating.
This sense of flow can arise in various circumstances: meditation, walking in the woods, perhaps a relaxing bath... or for no particular reason whatsoever - boom - just Life happening. This doesn't mean that there is no conception of apparent things or a sense of self. Once language, memory and conceptualizing have occurred it will never be unlearned. But it becomes secondary to the real-time momentum of process.
There is no thinking yourself into this (just as there is no thinking yourself into the aroma of freshly cut grass.) Just notice that it is already the case. There is sitting, reading, a car goes by, it's starting to rain... there is the activity of existence. Like the zen master said: no me, no bell, just the ringing. In this very timeless moment, no me, no rain, simply the happening of existence - boom!