It seems to me you don't have to be 50 to follow this recipe for a "younger" life.
Younger Next Year: A Guide to Living Like 50 Until You're 80 and Beyond*
by Chris Crowley and
Henry S. Lodge, MD
1. Exercise for 45 minutes six times weekly, both aerobic exercise and strength training.
2. Eat for nutrition, not for all the other reasons that people eat such as comfort, boredom, or easily available food.
3. Eat many fruits and vegetables.
4. Care for and commit to a wide circle of friends and other relationships.
5. Use your relationships to develop a support system.
6. Have a passion in life, a hobby, a reason to get up in the morning.
By the way - I follow these principles, and, at age 68, feel "young."