Grandpa is 92 years old and is still walking around,no alzheimer's, no disease, how? how can i be at least or better then that when i reach his age?

That's great!: To do as well as Grandpa, eat right, keep your weight down, exercise regularly including weights and cardio, learn to manage stress, don't abuse alcohol, tobacco or drugs, don't engage in risky behaviors, keep learning, fall in love and stay happily married. Good Luck!

Eat a healthy: balance diet, exercise regularly, no smoking, minimize caffeine and alcohol.... and the rest is out of your hands.