|(Image from kotaku.com.au)|
if you look at the research, older people have less anxiety and sadness and more overall satisfactionPlausible explanations are:
1) the aging process prompts the letting-go of not only material attachments but also the disappointment of dreams that will never be realized.
2) in every long life there are at least a few moments that inspire gratitude. Remembering them, a grateful person is a happy person.
3) a legacy (e.g., children, educating the young, or building a business) that engenders satisfaction.
No one likes "dead"-lines, but they do concentrate the mind.