It is very important to realize that demographics have changed: Less people having children, less people who even have a partner by the time they retire.

So to add to the list:

*Willingness to change/keep to healthy eating habits (notice I didn't call it diet)
*1 regular exercise activity that you enjoy doing several times weekly (can be walking, etc.)
*Living in a place that is warm, safe and quiet
*Engaged in a hobby or community activity several times per month or more often.
*Having a breadth of family contacts and reliable long standing friends across several age groups, whom you communicate and share common interests.
*Trying/learning a new skill that you enjoy. This can mean self-learning or taking a course/learning from more accomplished folks.