Complex sentence: During World War I, Bella Clara Landauer served as a volunteer in the American Volunteer Field Service (AFS Intercultural Programs), but this took its toll on her health and in 1923, her doctor recommended that she follow less taxing pursuits.
Split into simpler sentences: During World War I, Bella Clara Landauer served as a volunteer in the American Volunteer Field Service (AFS Intercultural Programs), but this took a toll on her health. In 1923, her doctor recommended that she follow less taxing pursuits.