The obvious answer is the darker pigmentation. I would suggest that it has a great deal to do with one's body and their reaction to sun damage and women with more pigmentation deal better with skin damage. There may also be more natural oil related to pigmentation that may be at your benefit. The later decades are also a time of loss. People do lose physical abilities.
Children grow up and away.
Loved ones die. My view would be that older people, at least many of them, become more realistic about life and death and that loss, although painful, is perhaps less shocking as it is to the young. The biggest difficulty with againg seems to come when too many losses pile up too quickly. Therefore, even the sturdiest people can be overwhelmed. But to get back to the point of satisfaction in life, I think it is definitely true that we have a greater chance of feeling satisfied if we can look back on our lives and begin to count up and enjoy our accomplishments.