Waterbending is a comfort to Korra. Water soothes. Water is home, Senna’s cool hands on young Korra’s scrapes and burns, of which there were plenty; is the calmness of Sifu Katara, the only person Korra would speak with after they grabbed her, kicking and screaming, from her home; is normality, something she was born into rather than the things that make her a freak.
Waterbending is part of a proud heritage, a community, a family. Something that’s inherently Korra, not Avatar, and the feeling of camaraderie and pride whenever she sees another Water Tribe descendent. It’s a feeling of closeness to her Sifu, a woman she looks up to perhaps more than anyone. It’s the flow of energy through her, and pure happiness— the closest Korra gets to spiritual is when she’s waterbending, really concentrating on the motion of the world.