David Ware, the founder and managing director of the telecommunications company TeamTalk, has resigned after more than 20 years.
Mr Ware - who started the business in 1994 - said he had hit a wall and been under huge stress with poor health running three companies.
He said he acknowledged his behaviour had been sub-optimal and staff have made complaints about him.
"I have been under huge stress for the few years running three companies, commuting between Auckland, Wellington and Timaru, while facing a challenging market situation and my health has gone downhill," he said.
Despite that, he said he has enjoyed running the company and was now taking some time out.
"I've loved running this company for the last two decades but the joy has gone.
"I haven't handled relationships well and the stress has taken a toll, so I'm heading to the farm to watch the grass grow," he said.
TeamTalk's board would now start the process of a finding a replacement.