Why care for Body? Why exercise? Why Surya Namaskar? Why Cow milk? Why Organic food? Why research? Why Swadhyay? Why Satsang? Why Empowerment of others? Why care for nature?
One answer for all questions.
The way universe (संसार), perceived by senses, is different than who ‘I’ is, body, senses, mind and intellect too are different from ’I’. So it is ‘I’’s duty to remain engaged in their nourishment and sustenance.
कर्मयोगी considers all of them(Universe, Body, Senses, Mind, Intellect) as subjects to be served selflessly. That’s why nourishing them is necessity of धार्मिक living. To keep Body/Mind/Senses/Intellect/Universe healthy and fit, is प्रभुसेवा. It is part and parcel of स्व-धर्म.