once in a blue moon

Once in a blue moon, a person is willing to do the hard internal work that leads to real, sustainable change.

Every once in a blue moon, our youngest daughter Amma has a Sunday soccer game; in that case, you’ll find me on the sidelines at her game.

It's a phenomenon - or, to use Chappell's terminology, a Femininomenon - that only occurs once in a blue moon.

As blue moons are not that common, it's thought where the phrase "once in a blue moon" comes from.

Kovacic's 64th-minute strike against Luton was one of those goals you see a defensive midfield player score once in a blue moon - no pun intended.