Hicks: that health is in some cases a good, in others a thing indifferent;
Yonge: Health is good for some people, but a matter of indifference to others.
Mensch: Health in some instances is a good, in others a matter of indifference.
Original text: καὶ τὴν ὑγίειαν τισὶ μὲν ἀγαθόν, τισὶ δ᾽ ἀδιάφορον.
I would interpret this as saying that our happiness is not dependent on our health.
See "setting up statues" for another use of ἀδιάφορον (ἀδιάφορως) (indifference/indifferent).
Hicks: But even when he has lost his sight, he will not withdraw himself from life: this is stated in the same book.
Yonge: And even, though he should lose his eyes, he will still partake of life (as he says in the same book). (i.e., Περὶ βίων)