Self-care is more than pampering yourself, eating right, and getting exercise. It is those things. But often it's also reaching out to friends, crossing things off your to-do list, forgiveness (of self and other's), and self-awareness.
A large focus of my work is self-care in high-stress tech spaces.
Here are some books I would recommend for that:
A disproportional number of coders are introvert, and the modern tech space is collaborative, open layout, and blurring the line between the personal and professional. Better understanding yourself and your needs as an introvert is part of self-care.