"IF I'D KNOWN THEN: Women in Their 20s and 30s Write Letters to Their Younger Selves," edited by Ellyn Spragins, DaCapo, 182 pages, $12.95 (nf)

Hindsight is 20/20, so they say.

Most of us have something we wish we changed about our lives, some action we stewed about at the time or a feeling better off banished.

In "If I'd Known Then," 20- and 30-something women revisit some of those events through candid and sometimes surprising letters to themselves.

The collection of voices is composed of actresses, athletes, activists, authors, entrepreneurs and artists. And each letter, which contains advice and insight, is preceded by a short biography that puts the women's thoughts into perspective.

"Sometimes you're your own worst enemy," singer/songwriter Natasha Bedingfield writes. "Don't be so serious. … Some parts of life have to be messy before they can become beautiful."

For Danika McKeller, who played Winnie Cooper in "The Wonder Years," waiting by the phone for a call that never came prompts the advice, "Just because your feelings are strong, they don't have to make you feel desperate."

Other wisdom imparted comes from author Hope Edelman — "Take Risks. Take them now"; artist Tara McPherson — "It's every child's birthright to be loved and cared for, even yours"; and professional surfer Mary Osborne — "You are afraid to take the path that is calling you."

It's hard not to relate to these letters on one level or another. Who hasn't felt loss or disappointment? Readers will leave "If I'd Known Then" inspired to look back on their own lives and write their own missive to themselves.

e-mail: jharrison@desnews.com