I worked as a pick packer for Woolworths for two years.
Epic money ($32/hr, $44 on Saturdays!), and it wasn't overly demanding. I was doing 4 shifts a week from 3pm-12am and was clearing $800 a week most weeks. It really is easy, at Woolworths you get an effective 'shopping list' of items and you just go from aisle to aisle to pack whats on the list. You usually got an hour to do around 100 items.
You were timed on percentage so if you worked fast you could feasibly take longer lunch breaks because management didn't really care as long as you finished the day at 85% (even with my hour-90 min long lunch breaks i never finished below 100%) so its not that hard as i said. Max weight lifting was like 16kgs? Most were 2-3kgs.
Of course, your pick-packing experience could differ from mine. Great money but in the end it ruined my studies because it is pretty draining so I left. If you like working independently (because aside from breaks you won't really talk to anyone) this is the job for you.