I was recently told to imagine the brain as though it were a tiny car inside your head with 3 people in it.
The ADULT is the one driving the car. This is the person who controls behavior and ultimately determines where you go - they hold the steering wheel.
The PARENT sits in the passenger seat, and is sort of the navigator. They hold the map. It is good to have them there to give you boundaries and direction, however, depending on how things go they can also be a source of guilt and shame.
The CHILD sits in the back seat. As long as everything is going smoothly up front, the child stays pretty quiet and doesn't cause any problems. Once the child senses something is amiss though, they can start to act up. The child wants everyone to get along, and they also want to do things that make them feel good. So they are not the best guide. They want pleasure without parameters.
When people are operating normally the adult drives along with the contented parent and child there with them. When the adult starts to question things, or can't make a decision, or doesn't know what to do, the parent and child will start to speak up and try to give their input. When the adult gives in to the inner parent or inner child is when bad decisions (and behavior) come into play.
There is also a part of the brain that controls the insula (or something like that). This is where the "gut feeling" that we can get comes from. This "gut" part of the brain is likened to our GPS system. This is really where we want to go. The challenge is getting ourselves in tune with this and listening to it rather than the parent or the child. In other words, you could think of this as the "walk by faith and not by sight" aspect. Or, perhaps think of this as where the Holy Spirit resides (in the Christian).
So our goal is to get the driver of our car to follow the "gut" part of our mind. This is when we find inner peace and contentment.
I don't know if I remembered all of this correctly, but it made a whole whale of a lot of sense when it was explained to me.