Throw out nonessential numbers. This includes age, weight and height.  Let the doctors worry about them. That is why you pay them.
Keep only cheerful friends. The grouches pull you down.
Keep learning. Learn more about the computer, crafts, gardening, whatever. Never let the brain idle. " An idle mind is the devil's workshop."  And the devil's name is Alzheimer's.
Enjoy the simple things.
Laugh often, long and loud. Laugh until you gasp for breath.
The tears happen. Endure, grieve, and move on. The only person who is with us our entire life, is ourselves.  Be ALIVE while you are alive.
Surround yourself with what you love, Whether it's family, pets, keepsakes, music, plants, hobbies, whatever. Your home is your refuge. 
Cherish your health: If it is good, preserve it. If it is  unstable, improve it. If it is beyond what you can improve, get  help.
Don't take guilt trips. Take a trip to the mall, even to the next county; to a foreign country but NOT to where the guilt is.
Tell the people you love that you love them, at every opportunity.
AND ALWAYS REMEMBER:
Life is not measured by the number of breaths we take, but by the moments that take our breath away.