Now that we're spending a third of our time at work, it's especially important to love what you do. Geriatric psychiatrist Gary Kennedy says seeking novel pursuits and being engaged in your life will keep you healthier for longer. Easton, 102, taught at Harvard University before becoming the dean of engineering at Rutgers in 1948. He spent 25 years growing the program from 200 students to over 2,000, and says today that his work was "deeply satisfying." More From Forbes: America’s Healthiest Cities World’s Most Dangerous Places to Breathe The ‘Healthy’ Choices That Are Costing You The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.