A British study found that the attributes of neighborhood open spaces (NOS) relevant to older people's life satisfaction were pleasantness, safety in and around the open space, and distance to it. Findings suggest that older people who have pleasant and safe NOS within a "comfortable walking distance" are more likely to be satisfied with life than those without.
Sugiyama, Takemi, Catharine Ward Thompson, and Susana Alves. (2009). Associations Between Neighborhood Open Space Attributes and Quality of Life for Older People in Britain. Environment and Behavior, 41(1), 3-21.