David McCullough is the Pulitzer prize winning author of John Adams and Truman, and he recently turned 79 years old. Harvard Business Review asked him, “Do you think about retiring?”

His response:

“When the founders wrote about life, liberty, and the pursuit of happiness, they didn’t mean longer vacations and more comfortable hammocks. They meant the pursuit of learning. The pursuit of improvement and excellence. In hard work is happiness.”

And at age 79, McCullough has just started a new book on the birth of aviation and he “can’t wait to get out of bed every morning.”

Are you sure you want to ever retire? Should you rethink your definition of retirement?