Several times a week, I walk past the Sunshine Flowers deli at the corner of 62nd and Lexington.

Every time I go by, I smile and get a bit of a boost to keep my happiness resolutions when I see the handwritten admonition on the side of the flower case to “Be nice.”

One of my Twelve Personal Commandments is to “Be polite and be fair.” I adopted that personal commandment years ago. I was about to get a promotion, and I was worried about whether I’d be able to do the job well. I mentioned this concern to my boss, and she said sternly, “Be polite and be fair. Then you’ll do fine.” I’ve always remembered that.

It’s important to “Be nice,” too. Henri-Frederic said the same thing, in a slightly more flowery way, “Life’s short and we never have enough time for gladdening the hearts of those who travel the way with us. O, be swift to love! Make haste to be kind.”

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.