Yes, to be more clear for the OP, I should have said any activity in your UA MP account. This could be *A flights, car rental, hotel, etc.
The point was that from Australia this won't be so easy as in the USA.
One thing that can be done is to donate as few as 1000 miles to a charity for the "activity".
However, doing that every 18 months will add up quickly to an infrequent flyer.
That is why I mentioned OZ, although they won't give as much credit for the cheap fares, their miles don't expire.