Etymology

Borrowed from Okinawan なんくるないさ. Literally, "things will sort themselves out". In standard Japanese: なんとかなるさ (nantoka naru sa).

Compound of なんくる (nankuru, “in that way”) +‎ 成い (nai, stem of 成いん (nain, “become”)) +‎ さ (sa, “emphatic”).
Interjection

なんくるないさ • (nankuru nai sa)

(Okinawa) Don’t worry, it’ll be all right.

This is what the word “Nankurunaisa” invites us to do: to accept the wisdom of time. To understand that if we persevere, time itself will sort things out. We just have to let things flow and add a bit of trust to what we do.