Complex sentence: During this time, McKinney supported himself by working as an arborist, trimming and taking down trees-he continued working in this field until the mid- 1970s, by which time he was appearing in major films.
Split into simpler sentences: During this time, McKinney supported himself by working as an arborist, trimming and taking down trees. He continued working in this field until the mid- 1970s, by which time he was appearing in major films.