Expanding the mind.
As well as reading, learning new things or skills is a great way to exercise the mind. Pick things you are interested in and find out more about them.
The internet is an amazing tool. It helps you explore the world from your own desk. There are heaps of lectures on you tube, and about one million blogs with awesome tutorials out there ready for you to discover.
When I read a difficult book, say The Odyssey for example, I always search online for an overview and a couple of video lectures that help support and explain the themes of the book. With this extra material I gain so much more out of the book than I would have on my own. It is really worth the extra time to expand your knowledge and gain extra insights that will enhance your learning experience.
Always strive to learn more. Our favorite saying in our business, and in our house, is "Google it!". If there is something you don't know then google it - the answer is out there, but first you have to look for it. The normal excuse of "I don't know" is no longer applicable.
We use Google for the girls too. They will come to me with a question, like "What noise does a moose make?", or "How do I draw a lassie dog?". And off we go to the computer to find out. How awesome it that. Take advantage of this amazing technology.
Pick a subject and explore.
Head off into your own adventure - no passport needed :)