Capybara
The capybara has achieved what behavioural scientists can only describe as total cortisol sovereignty. This remarkable rodent maintains heart rate stability that meditation instructors study with professional envy. When predators approach, the capybara often continues its current activity with such serene indifference that jaguars have been observed hesitating, as though questioning whether hunting something so unbothered might be socially inappropriate. In Japanese hot springs, capybaras have been documented entering states of relaxation so profound that researchers initially mistook them for deceased specimens. Their facial expression, whilst anatomically fixed, radiates a philosophical contentment that suggests they have solved problems Stoic philosophers spent lifetimes contemplating. The capybara does not manage stress; it has apparently eliminated the concept entirely from its operating system.