Marilyn Sellars (born December 31, 1944) is an American country music and gospel singer who had several hits during the mid-1970s on Mega Records, most notably the original version of "One Day at a Time" in 1974. == Early career == Sellars grew up in Dundas near Northfield, Minnesota. She started singing in church at the age of three singing "Oh, What A Beautiful Morning". Sellars began singing at functions and clubs around Minnesota as a teenager and after high... [more on Wikipedia]