The empowering variability of affordances of nature: Why do exercisers feel better after performing the same exercise in natural environments than in indoor environments?

•The specific impact of HEPA in nature's environments benefits from a person-environment system’s theoretical perspective.•In such a transactional perspective, psychological processes incorporate aspects of the environment.•Nature's affordances are less constrained than manufactured affordances.•The natural environment, due to its variability, solicits embodied and embedded actions.•Exerciser-nature interactions can be modulated by skill when solicited by affordances of nature.