"I just want to do this to prove to myself that I can get out and challenge myself."
Describing it as a mini sauna, he will put on 20kg of gear and set off on the walk.
"The jacket and clothing we wear doesn't really breathe well at all, so you basically soak in your own sweat for six hours.
"I'll have a tank on my back as well as well as my helmet and mask.
"So I have to make sure I hydrate really well, because getting fluids in is really hard."
To prepare for the lengthy walk, Adamson hitches on his firefighting kit after work and walks for about two hours.
"I go up the goat track as well and up Te Mata Peak, I just pick tracks that are quite difficult. It's been a bit niggly because I'm post-surgery for my knee as well, so I've had a couple of very close calls.
"About two weeks ago I was back on crutches and had my knee back in a brace, so I've had to be quite careful and keep an eye on it."
In terms of mental preparation, music is the key for getting Adamson through training.
"It's a great way to battle your way through things like this, but other than that I haven't really prepared for it at all."
The walk is particularly personal for him because his partner's mother died from cancer this year. "She's an absolute battler and I have her in the back of my head all the time. She's pushed me on and really supports me for a lot of this as well so that really helps.
"There's worse things in the world than doing a walk on a Sunday."
WHAT IS THE MEGA WALK?
A 28km run or walk, starting at Mitre 10 Mega Hastings at 7.30am and ending at Mitre 10 Mega Napier. Average time to complete is five hours.
There are three other options:
• The HALF MEGA is a 15km run or walk that starts at Awatoto - opposite the southern end of the Fertiliser Works - at 9am. It follows the Pathway and finishes at Mitre 10 Mega Napier.
• The SHORT MEGA is a 6.5km walk or run which starts behind Ocean Spa on Marine Parade at 10.30am.
• The MEGA MEANDER is a 3.5km walk or meander starting at 11am at Perfume Point, Ahuriri.
ENTRY FEES
• Adult (16+) $20
• Child (<15), senior (65+) $10
• Family (2 adults & 2 children) $40
• Team of 4 $60
• Under-5s Free
All proceeds go directly to CanTeen Hawke's Bay