Plan for your retirement on all fronts, financial and otherwise. Don't let it creep up unawares. If possible, retire gradually and use the time gained from partial retirement to rekindle intellectual interests.
A hobby that will stretch the intellect and keep diseases such as Alzheimer's at bay may be a good idea. Recent research has shown that the most important single factor in someone's lifestyle that delays the onset of Alzheimer's is the maintenance of an active social life. Choose interests and hobbies that involve social intercourse as well as thought.
Visit your family more often. Don't necessarily stay with them, but if you have the means, stay near them.
Travel more. Travelling is always difficult when working. Now you can travel freely without any worries.
Keep up with your old friends. One of the advantages of retirement is that it is a great leveller. The childhood friend who became a cabinet minister or a general is in a strange position once he has retired. He becomes the equal of the man has not been a great success, and between them, they may find a shared interest.
It is essential to beat stress by maintaining a structure to your life. Don't allow standards to slip, as that is the way to social isolation.