Tracing Down A Passage On Diathesis / Attitude

On page 186 of his text, DeWitt cites this interesting quote from Diogenes of Oinoanda: "The secret of happiness is in the diathesis, of which we are sole arbiters." The quote is cited as fragment 57 from the inscription, but apparently a different numbering system is being used by Martin Ferguson Smith here, nor do I find the numbering to be the same in Chilton's "Diogenes of Oenoanda - The Fragments." Both of these works post-date DeWitt, so he must have been working from another source. Does anyone know a good cite for this or know the equivalent in Smith's translation?

A follow-on observation about working with (1) the choice of attitude and also (2) the choice in the particular instance:

(page 193 of the text)