Well, when i was a kid i always wanted to make it to the guiness book, that i will be the longest living human being on earth. I wanted to live for more than 100 years.
But as of now i will be very happy with 80. How long do you want to live?
It depends on my health. If I'm feeling good, I'm still pretty sharp mentally, and am happy, I'd like to live to 100...why not? However, if I'm in poor health and just suffering, I don't think I'd wish to live very long.