Being only 56, I cannot relate. However, my math professor is 75 and does not act or look over 65. Physically and mentally she is unbelieveable.
Keep busy, keep active, learn something new everyday, make new friends and keep the old. Make someone smile, give away three hugs a day, brighten someone elses day.
If you don't start new projects, think of all the things you will miss sitting around waiting to die. What a waste.
My best to you.