Exercise has become so integral to my wellbeing that I barely separate physical health from mental health anymore. Neuroscientist John Ratey famously described BDNF as something like “Miracle-Gro for the brain.” search involving late-middle-aged and older adults has also investigated changes in BDNF following individual sessions of moderate continuous exercise and higher-intensity interval exercise, alongside changes in cognitive performance. For older adults, regular physical activity is associated with benefits across cardiovascular health, metabolic health, sleep, mental wellbeing, cognitive health, bone health and physical functioning. I think health span is the more interesting idea.