Complex sentence: In 1963 Waldron had a major nervous breakdown brought on by exhaustion and a heroin overdose; he recounted in 1998 that a lot of musicians felt that taking drugs was necessary for career progression.
Split into simpler sentences: In 1963 Waldron had a major nervous breakdown brought on by exhaustion and a heroin overdose. He recounted in 1998 that a lot of musicians felt that taking drugs was necessary for career progression.