He makes some good points. It's bad enough for you if you have to deal with someone you find difficult at work and you're stuck with having to deal with them every working day. Schwartz stresses how much worse it is when that person is your boss. Firstly, it's a natural stressor when you choose to believe you've lost control and / or are powerless. Both these situations will add to that. And, of course, when it's your boss, you've got a dollop of fear thrown in for good (bad) measure. Baseline security fear, the powerful kind. (Thanks Maslow.)
Schwartz uses a very helpful 'lens' metaphor as a possible solution. There's the lens of 'realistic optimism', the 'reverse lens' and the 'long lens.' The stress, the feelings of control and power and the fear are largely driven by how you choose to react to situations. So, choose to stop and look at it from some different perspectives. What are the facts and what am I telling myself about those facts? What is this other person feeling that is driving their behaviour? To what extent can I influence that? Ask some other questions about how this might play out and what can be learned and how important it is in the scheme of things.
So far, I've written from the angle of you having to deal directly with a difficult person of your own. If you're reading this, you're probably an experienced grown-up. You're probably able to take care of yourself instinctively. But how can you help your people who perhaps aren't as instinctively clued up?
I like Schwartz's approach of using questions, only instead of asking yourself, you engage your team member in a private conversation. They may come to you with a problem in dealing with someone else in the workplace. You cannot realistically give them some miraculous piece of advice that will work every time. You do not want to create a relationship of dependence with you having to always step in and solve others' interpersonal problems. But in engaging them with these questions, it'll drive them to think, not just with this person they're having difficulty dealing with today but in the future as well.
I read of a social experiment. Individuals were told they'd be working with a partner in a another room. Each would do one of two tasks, one of which was unpleasant. You got to choose who did what & your partner would never know. (Of course, there was no partner in the other room.) The researcher left for a few minutes while the subject decided. They had a coin in a sealed plastic bag in case they wanted to "decide fairly." 90% of non-coin tossers gave the crappy job to their partner. Of those who tossed a coin, the crappy job was given to their partner...
The only variable that made the decider make fairer decisions = putting a mirror right in front of them.