For green spaces to be most beneficial to health, they need to be walkable

It only makes common sense. Walk on a sidewalk in a garden, enjoy the beautiful flowers around as you are walking hand-in-hand with your GF (or BF) on a sunny day. Couldn't ask for more.

This does not bode well for Tokyo, who is looking to chop down those trees in Jingu

Want a succinct read over what this research means?

According to Andrew Rundle, DrPH, professor of epidemiology at Columbia Mailman School, one of the professors at the university that co-authored the study and specializes on urban design and neighborhood-level effects on health: “These results contribute to the growing evidence of how urban design affects the health and wellbeing in aging populations.” While he asserted that individual-level interventions to increase physical activity and reduce obesity are costly and often have only short-term effects, he also said: "[U]rban design can create a context that promotes walking, increases overall physical activity, and reduce car-dependency, which could lead to subsequent improvements in preventing diseases attributed to unhealthy weight.” We understand the research will appear in the publication Environmental Health Perspectives.

And, before you ask, there is no indication - at this point, at least - that the authors wish to link their study in any way to the 15-minute city concept.