All of these health behaviours are important but the social aspects - being socially integrated and receiving social support - are the most important.
This ranking alerts to two facts:
The factors that are most beneficial to health are not the health behaviours that appear on most medical lists: loneliness can create stress that can be deadly
While people understand the benefits of physical health behaviours, they don’t recognise the benefits of social behaviours.
Why is this the case?
Because they are not on lists like those above.
Because science (particularly medical science) doesn’t really have a good explanation of the importance of social factors for health. Scientifically, and practically, this is an unsatisfactory state of affairs.