Teachers, to me this was a very difficult poll, my own answer is "themselves" and the others answered differently, please explain in details.
We wouldn't want someone as wise as you to wear _____ out.
himself
themselves
yourself
oneself
I prefer yourself, on the grounds that if you simplify the sentence, I'd only say
'We wouldn't want you to wear yourself out'.
Rover
I think that in conversation you might hear any of the first three. You might also hear 'themself', though many people feel that this word should not be used - Themself or Themselves? (Disponible en anglais seulement)
Context is always important; labelling is rarely important.