Geraldine Cowan-Maere is losing her three teenage sons for two years, but the Bridge Pa mother is philosophical about her loss.
"There is a greater need," she said.
All are heading overseas as Mormon missionaries.
Peter is soon heading to Japan and twin brother Chesser is off to the Philippines. Next year, when he is 18, Benjahmon will start his mission.
The number of missionaries has increased since the Church of Jesus Christ of Latter-day Saints lowered the minimum age of missionaries by one year to 18.
"We found that on the break between school and heading out on their mission a lot of them lost the desire," Mrs Cowan-Maere said.
"The church doors are opening to more countries and more missionaries are needed. But you can't just turn 18 and head off - you have to finish your formal education first."
She said Peter thought his chances of becoming a missionary "were completely wiped out" after an accident that resulted in him losing a leg.
In 2010 he thought he was going to die after colliding with an oncoming car in Hastings while training for the IronMaori triathlon.
"But of all the reasons to not go, an artificial leg was not one," she said.
He is practising riding a bike with his prothesis - normally he drives everywhere.
Missionaries pair up for two years and live independently as flatmates.
"There is no contact other than letter writing and two phone calls, one at Mother's Day and one at Christmas. That keeps them totally focused on what they are supposed to do. Too many phone calls can break them out of the hard work, because it is hard work being in service to others."
She said her loss was similar to parents whose children opted to go to university.
"It is actually quite exciting - your child is developing values that will be instilled for the rest of their life: giving to others, compassion, love and service."
Church public affairs officer Angela McKee said there were currently 19 missionaries from Hawke's Bay serving in the Philippines, Singapore, Australia, United States, South Korea, Vanuatu, Italy and New Zealand.
"There are others waiting to go to South Africa, Japan and Canada.
"It is expected that by the end of this year 40 young men and women from Hawke's Bay will be missionaries around the world."