Activities

• Try Some New Mentally Stimulating Games: This has been talked about up above already, but you really should try to pick up a few. Even if you don't like to do these things alone, there are plenty of games you can try with friends, such as Scrabble, Quiz Games, Scattergories, or any game that will challenge you. Look at the impressive simulation video games out there as well, or a few of the puzzler ones.
• Expand Your Horizons: Doing new things in and of itself will help improve your mental endurance. Go see some live theatre, or maybe a different genre of film. Go to a museum or take a dance class (which will also give you great exercise). These are some examples of things that will help you keep a healthier mind over the years.
• Get Aerobic Exercise: This is generally defined as twenty minutes of repetitive, non-stop exercise—such as walking. You should really get at least thirty minutes if you can help it. Having this lower grade, constant exercise helps make your heart stronger and will give you a ton of health benefits if you do keep it up. Try to do it as much as you can, at least four times a week.
• Opt Out of as Many Conveniences as Possible: All I mean is take the stairs whenever possible. Walk to a store if it's in walking distance. Do your own gardening if you find that you have the time. Do more of the housework if you're so lucky as to have a cleaning service. Even activities such as housework can help keep you healthy—and can count as Aerobic exercise if you really do move non-stop.
• Make Goals and Keep a Record: This often applies to physical health. If you are trying to lose weight, for instance, weigh yourself frequently and write down your progress as the weeks progress. Make a series of small goals that you want to achieve, and document everything that may help you. You may want to record everything you eat, you may want to record how often you exercise, and you may also benefit from recording your personal feelings like in a "regular" journal. You can also keep records for mental health goals as well.

Your Record

If you spend the entire day avoiding physical effort (like avoiding stairs or putting off physical work), then mark yourself at "fault". If you spend the day on "mindless" activities, then also mark yourself at fault. When focusing on this goal, make some goals based on the activities above or on professional advice, and then mark yourself at fault when you fail to meet a goal or perform the activity.

Opinions

E. H. Chapin says, the successful are not those who wait for chances, but those who make chances. George Bancroft spent twenty-six years in writing his History of the United States. Thurlow Weed walked two miles through the snow with a piece of carpet for shoes, to borrow a book to study. Lincoln walked twenty miles to obtain a book he could not otherwise obtain. Horace Mann braided straw to get money to buy books. Cyrus W. Field was thirteen years accomplishing the laying of the Atlantic Cable. Robert Collyer, like Elihu Burritt, was a blacksmith. There was no American literature when Noah Webster began to make his Lexicography. He encountered difficulties which required enormous study. Eads accomplished a feat in engineering after opposition from all quarters during a long period. J. J. Hill constructed a railroad, despite the fact that it paralleled two existing roads, and ran through a country virtually unpopulated. Mitchel struggled against almost insuperable obstacles.

George Derby, James Terry White | The National Cyclopedia of American Biography

It is a favorite belief of mine that no student ever attains very eminent success by simply doing what is required of him; it is the amount and excellence of what is over and above the required, that determines the greatness of ultimate distinction.

Charles Kendall Adams

Golden Mean

Recommended Reading

Keep Your Brain Alive: 83 Neurobic Exercises — by Lawrence Katz, Manning Rubin

This book is aimed specifically at people who are afraid of their brain growing weak over time due to age. It has plenty of activities and tips for keeping your brain in shape.

100 Essential Steps For Healthy Living — by Angela Coldwell

This general guide book to healthy living was written by a successful business woman, and explains how she keeps her well-being despite the stress she faces every day.

Exercising Your Way to Better Mental Health: Combat Stress, Fight Depression, and Improve Your Overall Mood and Self-Concept with These Simple Exercises — by Larry M. Leith

This book explains how exercise can help improve your mood and mental health. As the title suggests, it contains exercises to help you achieve mental health with exercise.