Most people feel very comfortable with their daily routine. They know what will be taking place for the most part because it is so similar day after day. While it can feel comfortable to live like that your brain may be on auto pilot for much of it. If you want your brain to be healthier then you need to start experiencing new things. It can be as simple as taking a different route to get to work in the morning than you have for the past 7 years.
If you always read romance novels, pick up a good mystery and see how well you like it. You just might find that you have found a passion for something like this that you didn't even know existed before. Turn your favorite radio station to a channel that plays another type of music for a week. In that span of time you may have a new found appreciation for it. You may have learned the lyrics to some top hits as well that are in heavy rotation on that radio station channel.
A chemical called dopamine is produced in the brain. This is a natural substance that helps with moods. The more dopamine you produce the happier you will be. Research has shown that when the brain is exposed to new images and new experiences that it will begin to make more dopamine. As a result the ability to retain information about such events both in the short term memory and the long term memory are improved upon.
You can offer yourself some new challenges as well. For example instead of renting the newest movie on the top ten list rent a documentary on a subject you aren't familiar with. There will likely be a great deal of learning by the time you are done viewing it. You may have some questions as well that trigger your desire to find out more information about the subject.
New social experiences are a good idea too if you want a healthier brain. For example if you usually go to casual restaurants get dressed up and go out to one that is fancy. If you usually drive in the city take a cab or ride the bus. Allow your mind and your eyes to take in everything around you including the people and the scenery. Since you won't have to keep your eyes on the road the brain is going to be more receptive to things you likely overlooked on that same commute before.
As we experience new things our brain is learning and it is processing. This awakens a part of it that may have been dormant for a long time based on your same old routine. You will also find that you look forward to each new day when you have some adventure to look towards. You can experience new things on a small scale at first to get yourself comfortable with it. Then you can move on to larger ones like traveling to a foreign country or learning a new language.
The fact that your brain can continue to change and to build new neurological paths is very interesting. Don't waste the ability you have though to allow it to experience more than it has. Life is really too short to spend it doing the same things day after day. You will find you are happier overall when you add some adventures to your life.