Complex sentence: During the 1950s and 1960s he worked as an editor for "Science Digest", and in 1969 he moved to upstate New York with his wife, Susan, to begin a three-decade career as a freelance children's writer.
Split into simpler sentences: During the 1950s and 1960s he worked as an editor for "Science Digest". In 1969 he moved to upstate New York with his wife, Susan, to begin a three-decade career as a freelance children's writer.