Well, i worked for several years with the seniors, most of whom were in their late 80's and early 90's, one gentlemen who was over 100!! And they had allot of spit and vinegar as they would say

So, i think over 70 is getting there... but not "old" until about 85 or so and they can't function on their own too well anymore.
so i guess to me, getting "old" is when you can no longer function without someone helping you all the time.
And just to throw it in there... i've known allot of people in their 90's who were more passionate about life and everything it has to offer than most individuals in their 20's i know!
Sweetpea