How many of us believe in the idea that the way you think has some effect on your life? So your thoughts in someway create your reality.
Same thoughts always lead to the same choices, same choices always lead to the same behaviour, same behaviour creates the same experiences, same experiences produce the same emotions, same emotions drive the very same thoughts. Your brain is the record of the past, and all the things you have learnt and experienced. However, this behaviour affects your body because your body responds to what your mind is capturing/ has captured. So if you live in the past your body & brain will reciprocate automatically.
The only way to change your life you have to start thinking about what you have been thinking about and change it.