Complex sentence: He remained involved in the day-to-day management of Harman-Kardon until formally retiring on his 88th birthday in August 2006 and after turning 90 in 2008 remarked I don't feel much different than I did at 70.
Split into simpler sentences: He remained involved in the day-to-day management of Harman-Kardon until formally retiring on his 88th birthday in August 2006. After turning 90 in 2008, he remarked I don't feel much different than I did at 70.