Lenna Lowe studied art at Ohio Northern University and graduated from West Virginia Wesleyan College in Buckhannon. In 1899, she married Ellis Yost and took up residence briefly in Fairview and then in Clarksburg. In 1905, the Yosts moved to Morgantown so Ellis could study law at West Virginia University. Lenna Yost became involved with the city's Women's Christian Temperance Union (WCTU) in support of her husband's efforts to ban the sale of alcohol. As a member of the House of Delegates, Ellis Yost proposed the 1913 enforcement act of the state's 1912 prohibition amendment, known as the "Yost Law."
By 1908, Lenna Yost had become president of the state WCTU and turned women's suffrage into one of the organization's leading causes. As a member of the West Virginia Equal Suffrage Association, she led the unsuccessful campaign for the state's 1916 public referendum on women's suffrage. From 1917 to 1919, Yost served as the organization's president. In 1918, she resigned as state president of the WCTU to serve as the national WCTU's legislative representative and as the Washington, D.C. correspondent for the group's Union Signal.
In 1920, Lenna Yost returned to West Virginia to lead the drive to ratify the Nineteenth Amendment to the U.S. Constitution, granting women the vote. In March, West Virginia became the thirty-fourth of the thirty-six states needed to ratify the amendment. That summer, after the adoption of the amendment, Yost chaired the Republican National Convention which nominated Warren G. Harding for President. In 1921 and 1923, Harding appointed Yost to represent the United States at an international conference on alcoholism.
During the 1920s, she became more involved in Republican party activities, serving as the West Virginia Women's Activities Director. Yost campaigned actively for the election of governors Ephraim Morgan, Howard Gore, and William Conley, who in turn appointed her to the state Board of Education, the first woman to serve on the board. Yost served on the West Virginia Wesleyan Board of Trustees and was the driving force behind the construction of Elizabeth Moore Hall, a women's physicial education building at West Virginia University. She also used her national influence to place the first federal penitentiary for women at Alderson, Greenbrier County.
In 1922, Ellis Yost was appointed U.S. District Attorney for Southern West Virginia and the Yosts moved to Huntington, although Lenna spent much of her time in Washington, writing the weekly column for the Union Signal. The Yosts moved to Washington in 1930, when Ellis was named Chief Counsel for the Federal Radio Commission. Lenna accepted the post of Director of the Women's Division of the National Republican Party and spoke regularly on the role of women to take an active part in politics. She retired in 1934 at the age of fifty-six. In 1938, Ellis joined the board of Gordon Oil Company and the Yosts moved to Mt. Pleasant, Michigan. In 1947, he retired from the board and they returned to Washington, where Ellis died in 1962 and Lenna died in 1972 at the age of 94.