Almost four months ago, I stood at the northern tip of the North Island of New Zealand.

The new pack on my back weighed just over 17kg. I carried five days worth of food and two litres of water; though anyone looking at me would have thought I was carrying the kitchen sink.

I stared at the point where the two oceans (the Tasman Sea and the Pacific Ocean) met. Waves churned. According to Maori legend, the whirlpools where the currents collide represents the creation of life.

I thought that was apt.

Here I was about to start a 3,000km journey walking the Te Araroa trail down the length of New Zealand. Anything could happen; people told me it would be life changing.

Last week, part one of the #WalkNZ journey was completed – I reached the bottom of the North Island. 101 days. 1,688km walked.

As I strode into Island Bay on the south coast of Wellington, a tsunami of emotions pummelled into me like the churning waters at Cape Reinga all those weeks ago – awe, surprise, shock, elation, pride. But more than anything it was surreal.

I’d just achieved something I thought I couldn’t do.

When I had stood at Cape Reinga looking at the ocean, I had been nervous and scared. I had doubted myself, questioned what I was doing, and was worried about failing.

Those first few steps walking along the Te Araroa trail down to the beach, my parents waving me goodbye, were fraught and tears pinched at my eyes.

I was so out of my depth.

Then five days later, I hobbled into Ahipara having walked 100km down Ninety Mile Beach.

I was exhausted, bruised and blistered.

But I was also elated.

I’d just done the impossible and I was still walking – and I wanted to carry on.

I had a new-found confidence that walking the length of New Zealand was entirely doable and that I could do it.

Since walking off Ninety Mile Beach, I’ve wadded through a lot of deep, sloshy mud and pounded a lot of monotonous and hot pavement and gravel.

I’ve climbed several volcanoes – been forced to turn back 300m from the summit of one due to 110km wind gusts – and canoed down the Whanganui River despite fearing the rapids and capsizing.

I marched through waist-high and shoulder-high grass (coming up in giant red welts as an allergic reaction) and struggled through the Tararua Mountain Range in three long and brutal and muddy days.

I’ve wild camped, felt the pain of having 12 blisters at one time, serenaded paddocks of cows with my terrible singing, eaten way too many dehydrated meals (and not enough two-minute noodles), met some amazing trail angels, listened to the chorus of cicadas and native New Zealand birds, was told several times (mainly by old men) that I shouldn’t be walking solo, spent Christmas with my family, was recognised and approached by a follower of my blog, watched the sun set and sun rise from the summit of Pirongia, got a mean tan and mean muscles, walked through one pair of boots and four pairs of socks, peed over the side of a canoe, invited to have a breakfast of chickpeas and rice, survived one torrential down pour sleeping in my tent, the next one I woke up in a swimming pool, and another I watched from behind a window in the cosy confines of my friend’s living room.

The North Island has been both beautiful and terrifying; an experience you couldn’t totally prepare for and one worth more than any precious gem.

But it’s also been hard and for almost all those 101 days I’ve been in pain and out of breath.

The pretty pictures only speak some of the words. They capture New Zealand’s beauty but many fail to show the effort and pain to get there.

Because, make no mistake, the North Island has been physically demanding, often brutal and, at times, downright dangerous.

Add to that that my body has taken its sweet time to adjust and adapt to the rigours of walking more than 20km every day carrying a 17kg backpack, and the degree of the challenge goes up a notch.

Even now, almost four months on, I still wake up each morning stiff and spend about half an hour hobbling.

But the North Island hasn’t just been physically demanding; it’s been mentally demanding too.

For the most part it’s hard to just walk – there’s always a tree root or mud or car whizzing by that requires your attention.

I’ve been asked several times about how I must get all this thinking time when I’m on the trail. But I don’t. Thinking on the Te Araroa is a luxury; and it only happens when I stop walking.

To be so focused on where to place each foot, is mentally demanding. It’s exhausting.

And so, for the most part, my “thinking” while walking the North Island has consisted of cursing the trail, cursing my heavy pack and cursing the constant pain – whether it’s the feet, the legs, the hips, the shoulders, everything hurts. Always.

And it doesn’t matter if it’s uphill, downhill or flat, it still hurts.

To find the will to keep going when you feel the nerves pinch in your shoulder blades, when a new blister rubs, when your calves, lungs and heart all scream in unison as you push uphill, is hard.

To have to do it everyday, in torrential rain or in blindingly hot sunshine, while lugging a 17kg pack across terrain you thought only existed in the Amazon, is hard.

To have to do it when you haven’t showered for days, when mud is caked to your clothes and shoes and has stubbornly set up home under your fingernails, when the hiker hunger gnaws at you and the thought of yet another dehydrated meal for dinner leaves you depressed, is hard.

And to do all that solo (for the most part), without a friendly voice to jockey you along, to support you and motivate you – now that’s hard.

Ironically, it’s not the physical climbing of the mountain that is the hardest part; it’s the thoughts, the mind set, the mental toll, where the challenge comes in.

When I started #WalkNZ, I knew it would be hard but I thought I would get used to it.

How wrong I was.

Sure, I’ve become stronger, fitter but I’m still as far away, it seems, from conquering anything as I was when I took those first tentative steps away the Cape Reinga lighthouse.

I still question what I’m doing and I still doubt my abilities.

Reaching the Te Araroa plaque at Island Bay was epic, an achievement, an experience and, importantly, a journey.

But it’s only half the job done – and in my head, the second half, the South Island, is a job that’s tougher still.

And so, the physical and mental challenge continues.