The masters included a thesis on whether part-time workers were as engaged and productive as their full-time colleagues, and drew on a sample in the hospitality industry.
Contacts developed during the project led to his first job as a personnel officer at the Sheraton Hotel in Auckland.
After two-and-a-half years learning the HR ropes, Mr Jager got his first senior role, as human resources manager at the Sheraton Rotorua, where he was immersed for the first time in Maori culture.
"It was a fantastic place to grow up in the job," said Mr Jager. "They were warm people with great pride in their work.
"I was a young person finding my feet with a community of people who were very invested in the property, but also in the way they had done things in the past."
Changes needed to be made, and Mr Jager said he had to develop the ability to talk to staff about what management was trying to achieve and how they would benefit.
His next big challenge was back in Auckland with a shift into heavy industry when he spent 12 months as a human resources executive for Pacific Steel, with a strongly unionised workforce who were having to adapt to changed technology and new skill set requirements.
"During my time, we made more people redundant than we hired," he said.
A shift back to Sheraton as director of human resources and rooms led to a turning point after two years, when his wife, Debra, was pregnant with their first son. To stay on in hotel management would have meant increasingly committing to the hospitality sector's seven days a week, 365 day a year working life.
Instead, he interviewed for the job at Zespri, where he was initially based in Auckland and then took part in the relocation of the Auckland office to Tauranga in 2002.
"I initially thought Zespri would be a walk in the park after hotels," he said.
"I had no idea of the complexities of the industry."
Mr Jager became closely engaged in working with the senior team and picked up a succession of strategic responsibilities. He first added the role of general manager corporate strategy to his HR responsibilities.
He then became, in turn, GM for grower and government relations, and GM supply chain, working under Mr Marks, then Tim Goodacre.
"I learned an enormous amount from both of them," said Mr Jager.
Mr Marks had been a "stunning" marketer with a very precise and critical mind, while Mr Goodacre was one of the best agri-politicians he had seen, with a huge understanding of growers, who took personal accountability to deliver performance out of the system.
Tony Nowell served as chief executive for 15 months, and Mr Jager was confirmed in the top job in 2008.
Mr Jager has faced major challenges as chief executive, including Turners and Growers' bid to change the single point entry system, the China invoicing issues, and the ongoing Serious Fraud Office investigation.
However, Mr Jager said Psa was by far the biggest challenge he'd faced.
"And that's because of the impact it has had at the orchard level, not having any certainty about how the new Gold variety was going to go in the early days, and the uncertainty Psa created in international trade and with the workforce."
The kiwifruit industry had pulled together to try and make sense out of an uncertain and chaotic situation and then moved forward step by step, he said.
Working hard to have a home life
Lain Jager's key recreational activities are reading, mostly historical fiction, and getting out and about on the lifestyle block he and wife Debra own in Whakamaramara.
"I spend a lot of time walking around, spraying, moving stock and so on," he said. "I also try and get to the gym to keep up some measure of fitness."
The couple have two sons, Cai, 14, who attends his father's old school, New Plymouth Boys' High School, and Jed, 12, who is at Te Puna Primary School.
Lain Jager
Role - CEO, Zespri, since 2008
Age - 45
Born - Wellington, New Zealand
First job - Counter hand in family food businesses
Currently reading - The Pillars of the Earth by Ken Follett
Business as usual for Zespri despite probe
The ongoing Serious Fraud Office inquiry into the invoicing problems that saw Zespri having to pay almost $11 million in fines and reparations relating to its former Chinese subsidiary's actions is not taking up a great deal of the organisation's time, Lain Jager says.
"They have requested a lot of information and we've provided it," he said. "We presume they are working through it.
"In the meantime, there are certainly communications between the SFO and our legal team, but in terms of day-to-day matters it doesn't take up a lot of our time."
However, there was now an increased focus on ensuring the company's culture was compliance-oriented.
"We have to make sure our processes are robust around the world and that we're not exposed to any further weaknesses in our compliance framework," Mr Jager said.
"One of the things that changed for us is that it's no longer acceptable to say our own processes are compliant and our customers are responsible for their own compliance. In the new world that we live in, that's no longer acceptable.
"We're working closely with our customers to make sure our expectations about their compliance are crystal clear."
Former Zespri chief executive Tony Marks said Mr Jager was rarely hurried and could draw criticism for the momentum of some of Zespri's decisions.
"But the converse is that haste does not triumph over the right answer and each of the options has been thoroughly canvassed," he said.
"Lain presents a very stable, thoughtful analysis and recommendations on how best to handle issues."
