A book for older children, in which the phrase "exercise your courage muscles" is found, is the Kid's Guide to Working Out Conflicts by Naomi Drew (Free Spirit Publishing, 2004).
Picture books for children about courage include Rainbow Crow, by Nancy Van Lann (New York: Alfred A. Knopf, 1989). In this Lenape Indian legend a beautiful colorful crow finds the sun and brings it back to warm the dying earth that has a never-ending winter. It loses its colors in the process, but is never hunted by man again.
The Monster That Grew Small by Joan Grant Marshall (New York: Lothrop, Lee & Shepard, 1987). This Egyptian folk tale tells the story of a boy who is afraid of everything. With the help of a rabbit he goes on a journey to meet the "fear monster" and learns to face his fears directly, and to find courage.
The story, "Androcles and the Lion," found in most Aesop's collections, involves a runaway slave who helps a lion with a thorn in its paw, and makes a friend for life.
How Guinea Fowl Got Her Spots by Barbara Knutson (Cambridge: Carolrhoda Books, Inc., 1990) is an African folk tale, retold, about a small guinea hen that leads her flock in taking on a lion that is threatening her friend, the cow.
The Banza by Diana Wolkstein (New York: Dial Press, 1981) tells a Haitian folk tale about a small goat that plays his guitar and sings a song to keep up his courage and outsmart a hungry tiger.
In non-fiction books, Say Something by Peggy Moss (Gardener, ME: Tisbury House, 2004) addresses the importance of bystanders sticking up for those who are the targets of bullying.
Teammates by Peter Golenbock (New York: Harcourt Brace Jovanovich, l990). The story of Jackie Robinson and the racial prejudice he received when he was the first African-American player in Major League baseball, and how his teammate Pee-Wee Reese stood up for him during a game despite the prejudice of many of the fans and players.
The story of Ruby Bridges by Robert Coles (Scholastic, 1995) is the true story of Ruby Bridges the first African-American girl to integrate an all white school in New Orleans in the early l960s, and how she found the strength to walk to school each day past groups of angry white adults.
Molly's Pilgrim by Barbara Cohen (Bantam Books, 1983.) This is the true story of the author's grandmother when she first came from Russia to North America and was teased at school for her appearance and her accent. At Thanksgiving time Molly's mother helps to teach the class that modern-day immigrants are pilgrims too, and should be treated with the respect.
Biographies for children that touch upon courage include:
The Barefoot Book of Heroic Children by Rebecca Hazel (Cambridge, MA: Barefoot Books, 2000) offers short, biographical stories told in first person by young people who achieved greatness against tremendous odds.
I Can Make a Difference: A Treasury to Inspire Our Children edited by Marion Wright Edelman (New York: HarperCollins, 2005) is a collection of world folk tales, stories, poems and songs to inspire young people to see that even seemingly small acts of courage make a big difference to others and the world.