@lucaannibale My grandfather started in his late 60's. He said it was simple consistency. 1-2 hours of exercise a day, switching between cardio and weights.
The biggest thing he changed, though, was his diet. He eats simple, non processed foods, cutting down carb intake and completely removed sugar from his diet.
We had a deadlift competition this summer, and he was able to keep up with me to a 350lbs lift!
I really do believe you're never too old to get in shape.