"Cullen is awesome, he has an awesome personality and a great sense of humour," mum Shaye said.
Cullen also had a great sense of adventure; he loved motorbikes, trail bikes and tractors.
"The faster you go, the better," Shaye said. "If he hears any piece of machinery starting up at our parents' farm he is out there."
He also loved to go fishing with Poppa and even got up at 4am to go deep-sea diving with the family.
"We wouldn't change him for the world," Shaye said. "But life is harder; we do have to think outside the box.
"Everywhere we go we have to consider taking a wheelchair, and if we stay somewhere we have to take his toilet seat and showering seat."
The family had been doing therapy in New Zealand for seven years, but Cullen was still unable to sit.
Six months ago Cullen started Therasuit, an Australian-based therapy.
Cullen can now sit for as long as three minutes and stood on his power plate for the first time this week. "They have stripped it right back to basics," Shaye said. "We started with the same milestones as [16-month-old brother] Lochie."
Before Cullen would roll over by flicking his body to the opposite side, but now he can roll "normally" and prop himself up.
The family now want to continue the Australian-based therapy, but Shaye said it was not funded by the New Zealand Government.
The cost to go to Adelaide for the therapy would cost $15,000 along with $11,000 for the Therasuit clinics in Auckland on each visit.
The family was "blown away" when Sean Joyce from Action Sports Direct offered a 2017 Sea-Doo jetski and trailer worth $11,600 to raffle off to help cover the cost of Cullen's therapy.
People can buy a $20 ticket over the counter at Action Sports Direct or by messaging the Cullen's CP Journey Facebook page to go in the draw.
Joyce met the Wotherspoon family as customers and immediately shared a connection.
His 7-year-old daughter Clio was deaf and cannot hear without hearing aids, and also had to attend numerous therapy appointments.
When Joyce heard the family's plight to raise funds for Cullen's treatment, he and the manufacturers of Sea-Doo jetskis, BRP, came up with the idea to raffle off a jetski.
"They are such a beautiful family," Joyce said. "He [Cullen] just lights up whenever he comes into the shop."
The winner will be drawn on June 6, which is also Cullen's eighth birthday.
The family's ultimate goal is to have the Therasuit therapy funded by the New Zealand Government.
#Doingitforcullen raffle: When: 2pm, June 6 Where: Action Sports Direct What: To raise funds for Cullen Wotherspoon Cost: $20 per ticket