Mills is an advocate for “green” business. His belief in the importance of
sustainability has been widely publicised in New Zealand, and he has authored several articles on the financial benefits of a
green economy along with the need for New Zealand to take action on
climate change. He is the founder of Pure Advantage, a group of New Zealand business leaders lobbying for green economic policy. In 2010, the Pure Advantage Trust commissioned a group of world-leading economists to review New Zealand's
green growth opportunities. Prompted by a perceived lack of action from the Government on climate change, in 2014, Mills gave $64,999 to the Labour Party and $60,000 to the Green Party. In 2023, Mills continued his support of the Labour Party, offering to match up to $50,000 in donations. Mills' daughter Diana has also spoken to
Forbes about how her parents encouraged feminism in fitness early by promoting "strong is the new skinny". == Awards and recognition ==