In a famous experiment, Mike Merzenich taped the fingers of monkeys each day for 100 minutes to a sensor. At the same time they received headphones with music. He did this for 6 weeks.
Some of the monkeys were taught to focus on the feelings resulting from the sensors on their fingers, and notice any rhythm changes (by giving them rewards when they did). The other group of monkeys were taught to focus on the music and received rewards when they noticed changes in the volume.
After the six weeks, the experimenters compared the brains of the monkeys and noticed something remarkable. The monkeys that focused on the sensory changes showed a 2/3 increase in sensory cortex (and no increase in auditory cortex), while those that focused on the music showed a similar increase in their auditory cortex (but no change in the sensory cortex).
The result of this experiment was that experience and attention lead to physical changes in the structure and future functioning of the nervous system and specifically to the brain.
To me, this is absolutely remarkable, as it means that from moment to moment we choose who we will be, simply by the manner we use and focus are attention.
In fact, our daily choices are embodied through real changes in our brains. The power to disengage our attention from one thing and focus more on another is essential for our well being, and worth practicing. In fact, it is our gateway to brain plasticity. This is why I am convinced that our ability to willfully change the brain will become a central part of our lives. More on this soon:-)