Historically, retirement was a stage of life few individuals lived long enough to experience or enjoy. In the early 20th century, the average life expectancy was 47 years. As a result, most people worked until they became too sick to continue. Because the medical advancements and resources many enjoy today were not yet available, a majority of people died quickly of acute illness. Overall, time spent in retirement was only 7% of adulthood, or about 3 years.
In the early 21st century, 25% of one's adulthood can be spent in retirement. Because the average life expectancy as of 2019 is 79 years, those retiring at age 65, on average, can expect to spend 15 years in the role of the retiree, many even longer.