"We came back to a pantry full of food, constant income and our beautiful beaches. We are so blessed and are so grateful for what we have, but it is hard to come back knowing our skills are needed over there."
Travis will be the project manager for the building of a new child and maternity ward and Amy, who is a children's nurse at Tauranga Hospital, will help run the existing maternity ward.
"The current ward is tiny, way too small for the numbers we see in the heat of malaria season," Amy said.
"[It is] bat-infested, so run down and lacking the basics of even a wash basin to wash hands between patients."
Amy says the war-ravaged country is so developmentally behind and poor in healthcare services. She hopes to educate local community health workers and teach them basic health education.
"You see hunger every day. If these kids were born in New Zealand they would have had such a better chance at life," Amy said.
Amy remembers a child with diarrhoea who became dehydrated and died because there was not enough medical care available for them and she wanted to change that.
"It is simple diseases with such simple treatments. Some mothers have walked for days with really ill children just to get help," she said.
The Nilssons will exchange a comfortable bed and hot showers for a basic one-room dwelling with cold showers and minimal food in South Sudan.
"You basically feel like you are camping," Amy said, noting she and her husband are travelling light. Travis has taken tools unavailable to him in South Sudan and Amy takes basic medical supplies.
"We wish we could take a whole container full of clothes and food," she said.
Amy said her Christian faith was the key to helping her continue her work in South Sudan and whenever she missed home she would take time out to debrief.
Above all, Amy said serving in South Sudan was rewarding for the couple.
"It is a feeling you can't explain. The people are all worth it ... it is a life-changing experience.
"It is the heartbreak of knowing these people are not having the opportunities at life that we are having."
Amy encourages anyone who has entertained the thought of serving in a third world country to do it.
"They will never regret it."
• You can donate to the couple's return trip on givealittle.