Simplify the following text for a Grade 10 native English-speaking person.
Original: Before retirement he became a professor of psychiatry at New York University , a senior psychiatrist in the New York City Department of Hospitals , and a psychiatrist and the director of the Mental Hygiene Clinic at the Bellevue Hospital Center .
Simplified: He became a professor of psychiatry at New York University . He was a senior psychiatrist in the New York City Department of Hospitals and a psychiatrist and the director of the Mental Hygiene Clinic at the Bellevue Hospital Center .