Want to live a long and fulfilling life? Learn 3 key life lessons from a 101-year-old neurologist

Dr Howard Tucker, a 101-year-old neurologist, holds the Guinness World Records title of "Oldest Practicing Doctor″ and has now secured a new teaching position at Case Western Reserve University in Cleveland, Ohio, as he revealed in a recent video interview with Insider. Austin Tucker, his 26-year-old grandson, who talks to his grandfather almost daily and often helps him with technical challenges, is making a documentary about his life and 75-year career. Austin said that in order to live as long and as happily as his grandfather, he learns something new from him every day and tries to apply those lessons to his own life. Austin Tucker spoke to Insider about the three most important lessons he has learned from having Howard Tucker as a grandfather. (Also read: Longevity boosters: 8 healthy habits that can add decades to your life, as per researchers )

Howard Tucker's three lessons for a long and happy life

1. Keep learning and never give up

Howard Tucker passed the bar exam and was admitted to the bar at the age of 67 while continuing to work full-time as a doctor out of interest, Austin said. Even now, he added, his grandfather has difficulty using technology, but he is eager to learn and is always trying to grasp new concepts. Research suggests that having this trait may be linked to longevity. According to a small study that looked at the personality traits of 1,812 older people and 70 centenarians, being open and conscientious was associated with living longer. Austin Tucker said it was "huge" for him to observe his grandfather's approach to overcoming obstacles and not letting them get in his way. He explained: "If he's going to do something, he's going to do it 100%."

2. Hate is pointless

From his grandfather, Austin Tucker has learnt that holding grudges in your body is more harmful to you than it is to anyone else. When you get angry at somebody, when you dislike somebody, when you feel angry at somebody, it can have a physical effect on you. And it doesn't affect the other person in any way," says Austin Tucker. Howard Tucker and his psychiatrist wife have been married for 66 years, and according to Howard, the key to a happy marriage is compromise and recognising that you and your spouse are unique individuals. "If you're wrong, admit it. If you're right, shut up," Howard Tucker said. Research suggests that healthy relationships reduce the risk of death at any age and can even lessen the physical aches and pains associated with ageing.

3. Everything in moderation

According to his grandson, Howard Tucker's philosophy on living is "everything in moderation," with the exception of smoking. He claimed that his grandpa doesn't support drastic methods, either for good or bad. There aren't any fad diets or particular exercise regimens; simply everything in moderation. Don't make a steak supper a regular occurrence, even if you're in the mood for one, Austin Tucker said. Exercise is crucial, but you don't have to overdo it.

Previously, Insider revealed that Howard Tucker hits the treadmill a couple of times a week for two to three miles and that his diet consists mainly of fish, fruit and vegetables, with the occasional martini and scoop of ice cream. According to a new study, basic habits like these can add decades to your life. These simple habits include exercising, eating a healthy diet, getting enough sleep, managing stress and avoiding dangerous behaviours such as binge drinking.