Simplify the following text for a Grade 4 native English-speaking person.
Original: Martin Van Buren then retired to his home in Kinderhook . After being bedridden with a case of pneumonia during the fall of 1861 , Martin Van Buren died of bronchial asthma and heart failure at his Lindenwald estate in Kinderhook at 2:00 a.m. on July 24 , 1862 .
Simplified: In July , 1862 , Van Buren had a serious asthma attack and began to weaken .49 Van Buren died on July 24 , 1862 , at his home in Kinderhook , New York , of heart failure .382 He was 79 years old .