I’ve been thinking a lot lately about the importance of small treats, small pleasures. They’re fun to experience, of course, and I think they also have a very important role to play in happiness.

When we feel depleted and drained, and when we have no time or energy devoted to the things that give us pleasure, we start to feel exhausted, resentful, and angry. “All work and no play makes Jack a dull boy.”

But it can be surprisingly hard to think of what little treats you want to give yourself. So many pleasures come at a cost: cookies cost calories, movies and books take time and focus, a museum costs the price of a ticket. It’s good to have a list of treats and pleasures that have a very low cost in time, energy, or money.

For instance, I’ve become obsessed with the sense of smell, and I love the fact that a good smell can be enjoyed in an instant, with no cost. My latest favorite “treat,” which I save for moments when I need a bit of extra comfort or reassurance, is the fragrance  “Hay” from CB I Hate Perfume. It’s a warm, sweet, summer smell…of hay. I only put it on as a special treat. (Of course, it did cost me something to buy it, but not much, and never again.)

What small treats and pleasures have you found for yourself?  Be honest! Not things that you think you should consider a treat, or what you wish you considered a treat (you may or may not find going for a run to be a treat), but things that you actually do consider a treat. Even if these aren’t particularly estimable.

I want to lengthen my own list.

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. On her popular blog, The Happiness Project, she reports on her daily adventures in the pursuit of happiness. Gretchen is also on Facebook and Twitter.