The brain is an adaptive machine. It has been shown that meditation (specifically one that focuses on sensations) can increase the size of brain regions associated with attention and perception. Likewise, it can be assumed that living your life with focus on different things could lead to increasing in various areas of the brain. This actually coincides well with the self organizing theories mentioned in a previous post about the conscious observer.
How do you live your life? Do you focus on the things that you want to develop? Or do you constantly focus on the negative aspects – problems, unfulfilled desires, etc.? Which parts of your brain do you activate more and thus grow?