Despite her illness, Harper began shooting the film for UP this week in Vancouver, British Columbia, and is expected to wrap Aug. 11. The movie, also featuring Lauren Holly, Cameron Bancroft and Lucie Guest, will air in January.

"When I learned that the remarkable Valerie Harper was interested in working, I was so excited, because that meant she was doing well," Barbara Fisher, programming chief at UP, told the AP. "We are thrilled to have this iconic talent in our film and awed by her determination to live each day to the fullest. She is truly an inspiration."

"The Town That Came A-Courtin'," described as an "uplifting romance," is based on a novel by Ronda Rich. Harper plays the owner of a bed-and-breakfast who is trying to help kindle a romance between the widowed mayor of a Southern town and a successful author.

Harper, who starred as Rhoda Morgenstern on "The Mary Tyler Moore Show" and its subsequent spin-off "Rhoda," was told she may have "as little as three months left to live" in March 2013. Read more about her diagnosis here.

Harper's Broadway outings include Looped, The Tale of the Allergist's Wife, Ovid's Metamorphoses, Paul Sills' Story Theatre, Something Different, Subways Are for Sleeping, Wildcat and Take Me Along.