Have you given much thought to what your old age will look like? The Happiness Project suggests that we prepare ourselves as much as possible for a healthy old age—at least, as much as it is up to us. For instance, regular exercise, proper care of your teeth, and applying sunscreen are all part of the equation, as well as choosing to be happy and exercising your brain. What's your best tip for a healthy old age? Let's hear it in the comments.