Only among certain segments, such as middle aged men, is walking and cycling up.
The article blames poor walking/cycling infrastructure. Doubtless that is a factor. IMO, Crime and, for women, harassment and confrontations are also involved. A woman walking or cycling by is treated the way a man is who wears spandex, subjected to catcalls, jeers, suggestive remarks.
I walk and ride a bicycle. Nearly all my walking is done on errands and not purely for the exercise. Part of my cycling is the same. IMO, exercise as a lifestyle has to be intertwined with work, shopping, and other errands, the movements of daily life.