As I’ve worked on my happiness project, I’ve been struck by the paradoxes I keep confronting. As physicist Niels Bohr said, “How wonderful that we have met with a paradox. Now we have some hope of making progress.”

One of my Secrets of Adulthood is “The opposite of a great truth is also true” – and I try to embrace these contradictions:

1. Accept myself, but expect more of myself. This tension is at the core of any happiness project.

2. Take myself less seriously—and take myself more seriously.

3. Push myself to use my time efficiently, yet also make time to play, to wander, to read at whim, to fail.

4. Strive to be emotionally self-sufficient so I can connect better with other people. Only recently have I begun to understand the importance of this idea.

5. Keep an empty shelf, and keep a junk drawer.

6. Think about myself so I can forget myself.

7. Control and mastery are key elements of happiness; and so are novelty and challenge.

8. Work can be play, and play can be work. As George Orwell observed, “But what is work and what is not work? Is it work to dig, to carpenter, to plant trees, to fell trees, to ride, to fish, to hunt, to feed chickens, to play the piano, to take photographs, to build a house, to cook, to sew, to trim hats, to mend motor bicycles? All of these things are work to somebody, and all of them are play to somebody.”

9. The days are long, but the years are short. (Watch the video here.)

10. Happiness doesn’t always make me feel happy.

11. Flawed can be more perfect than perfection. In Japanese, there is a beautiful term, wabi-sabi, which describes the special beauty of the imperfect, the incomplete, and the transient. Superficially similar, but actually different in meaning (as I understand it), is the phrase from software development, Worse is better.

12. Spend out, to become rich.

Often, the search for happiness means embracing both sides of the paradox.

Take, for example, #1 above. W. H. Auden articulates beautifully this tension: “Between the ages of twenty and forty we are engaged in the process of discovering who we are, which involves learning the difference between accidental limitations which it is our duty to outgrow and the necessary limitations of our nature beyond which we cannot trespass with impunity.”

What are the accidental limitations, and what the necessary limitations? The first and most important of my Twelve Personal Commandments is to Be Gretchen, and this question is one of the most significant to consider.

From 2006 through 2014, as she wrote The Happiness Project and Happier at Home, Gretchen chronicled her thoughts, observations, and discoveries on The Happiness Project Blog.