Ever thought we could have two lines of thought processes ? I from personal experience certainly feel so. One type of thought process is which tries to act/think on lines of person's beliefs of what's right and wrong. This is what we can call as conscious thinking. These chain of thoughts are a formed from multitudes of factors from past experiences to situations the person has been in to external/internal influences. I personally believe this is what makes us human , separate from animals.
Ever get urges of doing something crazy which is out of character ? Ever had a brain fade moment where later you realize 'Oh , my God why did I do this ! ' . Everyone reacts differently to extremely emotional situations : Some people feel like puking ,experience moments where they are not able to think clearly , sometimes end up taking split second decisions.
I believe this is due to another type of involuntary thoughts born partly as reaction to situations. There are times , when you cannot think straight or your conscious mind is not able to direct. in such moments , i think we employ subconscious thinking , like a reflex action. Its often employed in times of facing extreme emotions of anger , happiness , sadness etc.
I think both parts have their own usefulness. Subconscious offers faster reaction time but the validity of decisions depends on your past learnings, genetic factors and generally slow to change. Also it's the default Go-to method for the brain. On the other hand, Conscious mind could have a slower reaction time , but has a higher probability of taking correct decisions.
Consciousness is constantly evolving in nature and will revolve around your what u absorb over the years and believe in. That's why i guess they say to be around positive influences , environment and think good things because it frames your conscious thoughts. But converting them to subconscious thoughts is a much harder process of employing discipline and ones who can do can achieve great things since they see clearly more than others and can react more quickly than others.
So i would end philosophically by saying this : Consciousness is what you want to be and Subconsciousness is who you are and life is all about learning to be who you want to be by transforming your conscious thoughts to subconscious thoughts.
Note : All images are taken from Google and are not owned by me and only used for reference purposes.