I think a better question would be "when is one old?" I just turned 70, look 55, feel 30, and have no aches, pains, illnesses or physical problems of any kind. So while 70 sounds old to a 20-year-old, I cannot think of myself that way.
我觉得问题换成：“一个人什么时候才算老？”更好。我刚刚70岁，看起来像55岁，感觉自己才30，而且并没有任何病痛缠身。70岁让20出头的人听起来老，但我并不觉得自己老。
My maternal grandmother lived to be 102. My paternal grandfather lived to be 99. I have good genes, so I figure I'll live another 30 to 40 years, barring any unforeseen incidents.
我的外祖母活到102岁，我的祖父活到99岁。我有这么好的基因，我认为我可以再活个三、四十年，除非发生不可预知的意外。
It makes my heart glad to see all these answers on Quora of people in their 70s, 80s, and beyond. Because I used to think that at that age, you can't deal with change or technology -- but these people do and they use Quora to help those of us who will be approaching those ages soon enough.
很高兴可以在Quora看到七八十岁甚至更高龄的人的回答。因为我曾认为到了那个年纪，你就没有办法跟上变化和技术，但是这群人却可以，他们使用Quora来帮助我们这些即将踏上高龄的人。

So I want to thank all the "old" posters here and I hope that when it's my turn, I can do the same for the next generation.
因此我想在此感谢那些”老"答主，也希望轮到我的时候我也可以像这样帮助下一代们。
I'm 99 - will be 100 in 7 months. I live independently in my home. I hear ok with aids, see 20/20 - drive night/day. I was married 70 years to the love of my life - lost her 7 years ago. I have great children and their wonderful families, but all live in different parts of the country. I'm an active member of several organizations, like to read. I had a girl friend, a very lovely lady (only 90) I met 3 years ago. She just passed away. Is death imminent? Define imminent. Enjoy life.
我已经99了，在过7个月就100了。我独居，需要佩戴助听器、视线依旧不错，白天黑夜都可以开车。。我与我的一生挚爱结婚70年了，她在7年前去世了。我有许多孩子，都组建了自己美满的家庭，但是都居住在国内各地。我是几个组织的积极成员，比如说阅读。我曾经还有一个女朋友，是位非常可爱的女士（才90岁），我们在三年前碰过面，但她去世了。死亡不远了吗？你应该先告诉我什么叫“不远”。享受生活吧。