Don’t retire until you have truly exhausted your love for your work. Don’t retire without some plan to keep busy at something other than recreation. Keep intellectual pursuits high on your list of activities.
Understand and adjust to what retirement can mean in terms of too much togetherness with your spouse. Give each other space as existed when you were working.
Accept aging and have a good sense of humor about it. Stay active, be social, and generally good health will follow.