Much of what is visible could be a tiny/random/invoked reflection of that vast abyss from layers in the subconscious sphere,and considering the enormous magnitude of constant filtering/processing exercise done by human brain ,it may be too difficult to consciously make choices all the time.
Human brain lies amidst large bit of themes/phobias /information from present or past,real or illusory ,but human mind is able to further it down to about may be 50,and then may be 7-10 of them kept in short term memory at particular phase .
What remains visible to human at a given time is select,condensed,filtered theme/narrations and decision/action at particular point is prompted by ones mental state at that moment,one could be in haze of few consideration and any stimuli alters the preferences of themes and bias ones perception to arrive at a conclusion at that point,which usually becomes a decision with considerable implications and could not easily be undone.
At all given points in day or night,awake or sleep,mind flows in select,few condensed field of information/imagination generating/surfacing into thoughts ,further men attempt to analyse to built notion/perception about what lies around him at present or could be in future and further as if men remains in a constant pattern of decision making mode about his choices making /forming his pattern of belief/personality.
At any given point unconscious mind have huge stored data of which sources are innumerable and may not always be traceable ,may lie in deep childhood ,other experiences imaginations, further based on what one has heard,seen ,read or visualizing in state of deep trance ,where connections are connected to unknown sources . And what it retrieves unconsciously forms a pattern /predispositions/habits/addictions etc reflecting in a typical sort of personality,but when retrieved it is with deep bias and flicker upon quality of mind at present moment which also cause it to glean or darken.
Mindset is formed over a period of time reflecting in a way one forms notion ,attitudes deeply in unconscious state ,which occur in its pattern beyond much conscious realm ,developing a personality which either be volatile/stable or complex else ,and accordingly causing reactions.