Conscious experience as such is an exclusively internal affair: Once all functional properties of your brain are fixed, the character of subjective experience is determined as well.

Someone who cannot stop his outer flow of words will soon be unable to communicate with other human beings at all.

As far as inner action is concerned, we are only rarely truly self-determined persons, for the major part of our conscious mental activity rather is an automatic, unintentional form of behavior on the subpersonal level.

Speaking as a phenomenologist, it seems to me that a considerable portion of mind wandering actually is "mental avoidance behaviour", an attempt to cope with adverse internal stimuli or to protect oneself from a deeper processing of information that threatens self-esteem.

As modern-day neuroscience tells us, we are never in touch with the present, because neural information-processing itself takes time. Signals take time to travel from your sensory organs along the multiple neuronal pathways in your body to your brain, and they take time to be processed and transformed into objects, scenes, and complex situations. So, strictly speaking, what you are experiencing as the present moment is actually the past.

Subjective time flows forward, the phenomenal self is embedded into this flow, an inner history unfolds. That it is why it is not a bubble, but a tunnel: There is movement in time.

When you are simply observing your breath, you are perceiving an automatically unfolding process in your body. By contrast, when you are observing your wandering mind, you are also experiencing the spontaneous activity of a process in your body.