Looks like good training Doug. Do they require hikers to pass a fitness test before being granted the ok to walk the track ?
The short answer is no, there is no fitness test.
There is an excellent incentive to be fit enough to complete the track though. If you are simply not fit enough or too tired to walk then your only other choice is to charter a helicopter to come pick you up.
Helicopter charters in ANZ cost around NZ$1600 per hour and as they tend not to park helicopters along the track you would need to pay for the time to prepare the helicopter and for it to fly in, pick you up somewhere flat (not many of these spots) and fly out again. Probably a minimum of two hours and more likely three hours.
It would probably be better to fall and injure yourself so that you are unable to walk because then ANZ's unusual accident insurance scheme would kick in and they would pay for the medical evacuation. We have a universal accident insurance scheme (called ACC) that automatically covers every person in ANZ including tourists (and which I pay for in my taxes).
Apparently one of the guided hikers fell on the last day of my hike and was injured and helicoptered out. I didn't see the incident but while I was waiting for the boat pickup at the end of the trail some of my fellow independent hikers who arrived after me had seen the incident. The man fell on a difficult strip that is similar in some ways to the ridges in the rock on the descent from Roncesvalles to Zubiri.
There was one (Kiwi) woman of a similar age to me (impolite to ask) who was walking with her son. She was short but a reasonably experienced hiker. She laughingly told me that her son (big, tall DoC Ranger) was there to carry the heavy stuff for her and offered his services to me on a couple of occasions when we met on the trail and I was probably looking a bit exhausted
The next oldest were two other Kiwi women in their 60's who were also reasonably experienced trampers but who were unfit. On the longest day (3rd day) it took me 9 hours hut to hut and I struggled at the end. The two women in their 60's hadn't turned up after 11 hours and we were starting to get a bit worried about them when they finally walked into the hut.
If someone wants to do this tramp but isn't sure if they can do it then I would suggest either doing a shakedown hike like the Abel Tasman coastal track first because it is slightly easier but more importantly has good coastal access by boat along the whole track and so if you need to bail out then it is simple and cheap to do so.
Alternatively, book yourself in for the guided walk because these hikers get an additional day to walk and so the distance covered each day is shorter and (importantly) all your food is taken care of for you and so you don't need to carry it which makes your pack much lighter and you can even get an upgrade to use their bedding, saving additional weight and you can even get your main pack transported for you at a cost. The cheapest guided option costs around NZ$2500 (bunk room) and the most luxurious around NZ$6800 each (double room with single supplement if only one person).
I did the Abel Tasman coastal track on my way south and this not only helped me sort my gear and get rid of a couple of extra kilos of unnecessary gear but also helped my overall trail fitness.
I probably should add that it is quite difficult to get a spot as an independent hiker on the Milford track. Only 40 people are permitted to hike each day and you need a reserved slot.
This year, the day that reservations opened it was completely booked out within 45 minutes. Initially I missed out and I just happened to be looking at the website about a month later when someone cancelled their slot and it suddenly became available and so I grabbed it immediately. Talking to some of the other hikers it seems like they had a similar experience and so if you don't get a slot on opening day then keep browsing the website from time to time and something may well open up for you.
