Dorothea Brande was an American writer and editor, well known for her books Wake Up and Live and Becoming a Writer (a useful resource for writers, by the way).

In Wake Up and Live, she suggests twelve mental exercises to make your mind keener and more flexible. These exercises are meant to pull you out of your usual habits and to put you in situations that will demand resourcefulness and creative problem-solving. Brande argues that only by testing and stretching yourself can you develop mental strength.

Even apart from the goals of creativity and mental flexibility, Brande’s exercises make sense from a happiness perspective. One thing is clear: novelty and challenge bring happiness. People who stray from their routines, try new things, explore, and experiment tend to be happier than those who don’t. Of course, as Brande herself points out, novelty and challenge can also bring frustration, anxiety, confusion, and annoyance along the way; it’s the process of facing those challenges that brings the “atmosphere of growth” so important to happiness. (It’s the First Splendid Truth: to be happy, you must think about feeling good, feeling bad, and feeling right, in an atmosphere of growth.)

I have to confess that I’ve tackled just a few of Brande’s mental exercises – #6 and #10 – and only because they come naturally to me, which is hardly in the spirit of the exercises. I have toyed with the idea of trying the others.

Here are Dorothea Brande’s twelve mental exercises. Note: she wrote these in 1936, so you need to adapt of few of them.

1. Spend an hour each day without saying anything except in answer to direct questions, in the midst of the usual group, without creating the impression that you’re sulking or ill. Be as ordinary as possible. But do not volunteer remarks or try to draw out information.

2. Think for 30 minutes a day about one subject exclusively. Start with five minutes.

3. Write a letter without using the words I, me, mine, my.

4. Talk for 15 minutes a day without using I, me, my, mine.

5. Write a letter in a “successful” or placid tone. No misstatements, no lying. Look for aspects or activities that can be honestly reported that way.

6. Pause on the threshold of any crowded room and size it up.

7. Keep a new acquaintance talking about himself or herself without allowing him to become conscious of it. Turn back any courteous reciprocal questions in a way that your auditor doesn’t feel rebuffed.

8. Talk exclusively about yourself and your interests without complaining, boasting, or boring your companions.

9. Cut “I mean” or “As a matter of fact” or any other verbal mannerism out of your conversation.

10. Plan two hours of a day and stick to the plan.

11. Set yourself twelve tasks at random: e.g., go twenty miles from home using ordinary conveyance; go 12 hours without food; go eat a meal in the unlikelist place you can find; say nothing all day except in answer to questions; stay up all night and work.

12. From time to time, give yourself a day when you answer “yes” to any reasonable request.

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Gretchen Rubin is the author of The Four Tendencies, her most recent New York Times bestseller about the groundbreaking analysis that reveals the one simple question that will transform what you do at home, at work, and in life. She has also written three other bestsellers, Better Than Before, The Happiness Project, and Happier at Home. She writes about happiness and habit-formation at gretchenrubin.com. Follow her here on LinkedIn by clicking the yellow FOLLOW button, on Twitter, @gretchenrubin, on Facebook, facebook.com/GretchenRubin, and listen to her popular podcast, Happier with Gretchen Rubin.