I don't want to be a kill-joy but have folks considered the time difference (i.e. jet lag - 13hrs diff to Wellington at present) and season (i.e. Winter?) in NZ?
I attended a conference in Brisbane some years back and never got adjusted so felt v. tired, others adjusted and felt fine (I used to do a lot of long haul traveling and suspect the effects of jet lag just accumulate ).
South Africa is not a big time zone jump unless you are from New Zealand.
Just to be clear, I would love to visit NZ but if that ever happens it will be a long vacation so that I can adjust and enjoy it - just about everyone I met who went there wanted to go back (and get a job there!) - and that was long before the JRRT stuff.