As part of my recent book tour, I visited San Francisco. I had a free afternoon, so I walked from my hotel to my old apartment, where I lived for about a year before I went to law school.

As I walked there, I tried to remember the details of my life in San Francisco. I have no recollection whatsoever of going to a grocery store or a restaurant or a book store.

I have odd patches of memory. The big hill I had to climb on my running route, and the bagel store I went to every morning, and a long walk that I took with my roommate one day, and the salads we loved so much that we would go to Berkeley to get them.

One of my more poignant Secrets of Adulthood is:

Never forget how easy it is to forget.
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I wish I could tell my younger self: Make a photo diary before you leave this place! You think you won’t forget, but you will! Instead of taking photos of unusual sights, take a photo of the most usual sights. In the future, you’ll be a lot more interested in seeing a photo of your dorm-room closet or your laundromat than seeing a photo of the Louvre.

How about you? Do you ever wish you had photos from ordinary days in the past?

Gretchen Rubin is the author of the #1 New York Times Bestseller The Happiness Project—an account of the year she spent test-driving the wisdom of the ages, current scientific studies, and lessons from popular culture about how to be happier—and the recently released Happier at Home. On her popular blog, The Happiness Project, she reports on her daily adventures in the pursuit of happiness. For more doses of happiness and other happenings, follow Gretchen on Facebook and Twitter.

*Image courtesy of www.alainpicard.us.