"In those books, there are only a few paragraphs written from my perspective," he says.
"But EM-PA-THY is me."
Growing up in Washington DC as an African American, and (for many years) a closeted gay man, Hillman had to battle from the outset. He remembers the United States on fire the night that Martin Luther King jnr was assassinated; how it was the moment he realised race was a "real thing" in that embattled nation.
He was smart and academic, but from a poor neighbourhood. His parents always encouraged him to have a voice, loved him unconditionally, and his family modelled the art of empathy.
"We [my four siblings and I] were raised in the black Baptist church with a premium on respect for others, good manners and having a giving spirit. As a closeted gay teenager, I knew that my siblings knew I was gay, yet I really appreciated how they never confronted me, instead waiting for me to find myself and be an authentic person with them."
The strength of empathy was also taught to him at college. As he shares in the book, he was awarded a scholarship to Muhlenberg College at 18: one of a very few black students on the campus. Here he was a kid in a sea of white people; struggling to fit it.
That was until the invitation to join a Jewish fraternity (the only fraternity that extended their hand to him) changed his life.
"I can personally attest to the impact a sense of belonging has on confidence and performance," he writes.
From a low-performing first semester, to a strong grade average and a huge boost of confidence after his inclusion in the fraternity, empathy was a game-changer.
Hillman's subsequent career was stellar. As a clinical psychologist, with a Master's degree from Harvard, he worked on the front line in the community, before moving into leadership training at the US Air Force.
He was recognised for the excellence of his work and chosen as one of seven Air Force officers to go to Washington DC as part of a commission to investigate the military's existing position around homosexuality.
Instigated by Bill Clinton after his election to office in 1993, the commission was to look at ways in which to overturn historical rules banning homosexual people from the military.
But rewind seven years, and Hillman had experienced this bigotry himself. When he joined the military, he had to sign a document asking if he'd ever engaged in homosexual activity. He had answered "no".
"Although I had been suppressing my homosexuality for years, and I was married and had two beautiful children, I'd never had to tick a box," he says.
So, in 1993, still married, still hiding the truth, he found himself seated in a room with other military high-brass, listening to arguments for and against homosexuals being allowed in the army.
The result was "don't ask, don't tell". You could no longer ask "are you gay?" or pursue witch hunts in the military. But the implication was "being gay is shameful. Don't let anyone know".
Hillman received a meritorious service medal - a high honour – for his service in this commission. It was a Pyrrhic victory: public acclaim, private shame. No longer able to live a lie, he decided to embrace his reality.
"The month 'don't ask, don't tell' was announced, I left the military. I told my wife I was gay: it was the most difficult conversation I'd ever had with a person. But I was received with so much love."
He was no longer hiding; no longer torn in two.
After a stint on Wall Street ("I'd always dreamed of living in New York, but it was so different to what I thought. "I actually had to listen to Eminem every morning to get myself into the aggressive mindset of that world".) Then Fonterra came calling, he was headhunted, working as global HR director and director of talent and OD.
And he fell in love with New Zealand.
"Even though many migrants often comment on how insular Kiwis can be and how much effort is required to break into the fold, I personally have found New Zealanders to be warm and welcoming, which is the main reason why I have decided to spend the rest of my life here."
Since 2007, Hillman has under the banner Sigmoid Consulting, his business leadership and transformation consultancy. But when Covid hit his "business fell away and I was left with a lot of time, which I was able to spend writing".
He agrees when I ask if he feels that the "stars weirdly aligned" for the book over the lockdown period. Particularly as the power of empathy (and its opposite) was illustrated so powerfully by the leaders in both Aotearoa and his home country of the United States.
The leadership demonstrated by Jacinda Ardern and Donald Trump act as exemplars of two opposing styles. One typified by empathy, the other by arrogance.
"Ardern united an 'army of five million' to combat an invisible and insidious enemy, which made New Zealand a global benchmark," he says.
"Trump divided a nation by politicising the wearing of masks, downplaying Covid as a hoax until he could no longer ignore the shocking number of deaths, and then refusing to model safeguards once he was diagnosed. For many Americans, his leadership was seen as non-empathetic, where he put his own self-interests above the well-being of more vulnerable citizens."
Trump's opportunistic, self-obsessed and arrogant leadership is a warning around how tone-deaf leaders can so readily fail.
Hillman gives the example of Trump's refusal to denounce white supremacists in the aftermath of the face-off in Charlottesville, Virginia.
"Trump's infamous words, 'there are good people on both sides of the argument' led to Biden's decision to run and the resounding vote to remove Trump from office.
"The big lesson here is, when you disenfranchise people and make them feel worthless, they become more susceptible to any potential leader who will help them feel they truly belong and matter."
Emotional intelligence has become integral to effective corporate culture. In EM-PA-THY, Hillman draws upon case studies to illustrate the power of empathy in creating strong, resilient, connected workplaces.
And he believes that a healthy work culture, underpinned by empathy, is something younger generations are demanding. And given the battle for skilled workers internationally, leaders are being forced to listen.
"I do believe that the younger generations have more of a sense for how empathy is vital for connection and influence, as well as for strong relationships," he says. "They have a real sense that they should be listened to and treated fairly."
Hillman believes that a new emphasis on mindfulness training in New Zealand and globally ("which is infused with a great deal of empathy") is teaching young people the perspective of other people and the impact that has on personal connection.
The process of developing empathy can be hard for those who've prided themselves on old-school authoritarian leadership. Hillman says there needs to be a shift in thinking, fuelled by personal insights, for it to take place.
"Older bosses in professional services firms are coming to grips with the reality that, to keep younger employees engaged and motivated, it's important to tap their thinking and perspective on a number of issues," he says.
He says the huge raft of empirical data supporting the role of emotional intelligence in attracting and retaining the best talent in organisations is also a big motivator.
But as New Zealand continues to win the battle against Covid-19, the power of empathy in a leader is played out in our country on a daily basis. That could be the biggest motivator of all.
EM-PA-THY: The Human Side of Leadership by Harold Hillman, Bateman Books, August 12, $29.95