Writing this on the morning of the 15th February, 2014.  I am exactly 76 years old today.  Life goes on as usual.  Normal activity such early morning jog around 5 km, followed by light calisthenics in the room, with light weights of barbells and dumbells.  Feels good.  Nice to do physicalworkout and have a sweat.
Yes, to be healthy at this age is very important to me.  Always in my mind:  You must work hard for your health.  And that, is exactly what I always do.  And I love every moment of it.
There is another interesting phenomena that I noticed.  When I was 60, I could do the 10 km run in 60 minutes. At 70, the time taken: approximately 70 minutes.  Maybe when I am an octogenarian, I might be able to do the 10 km run in 80 minutes?  Hopefully so.  Its a target eagerly looking forward to.