Even more generally it can be taken as a paraphraasing of the Litany of Gendlin

Jack Sparrow: The only rules that really matter are these: what a [person] can do and what a [person] can't do. For instance, you can accept [reality] or you can't. But [reality] is [true whether or not you believe it], boy, so you'll have to square with that some day ... So, can you [accept it], or can you not?