I’ve had some great bosses throughout my career, people who encouraged me, challenged me and helped me become a better leader. I’ve also had a few who taught me lessons they probably never intended to teach. One of those lessons came during my first year as a pharmaceutical sales representative at Upjohn. I was young, ambitious and determined to succeed. Landing that job was a big accomplishment for me, and I wasn’t about to let anything stand in my way.

Unfortunately, my first boss wasn’t exactly a shining example of leadership. Some days she was friendly, encouraging and helpful. Other days, she could be downright miserable. You never knew which version of her was going to show up, and that uncertainty hung over everything we did.

A Long Day in the Car

I’ll never forget one particular day. We spent hours together in the car, driving to see customers across South Florida in the middle of summer. The heat and humidity were miserable enough on their own, but spending the entire day with her made them almost unbearable. From the moment we pulled out until the moment we got back, the conversation was negative. She complained about the company. She complained about people in the company. When she ran out of those things to complain about, she focused on everywhere I was falling short. Not once did she say anything positive about me, my colleagues or the company we worked for. By the end of that drive, I wasn’t motivated. I was deflated. For the first time, I seriously questioned whether I’d chosen the right career and the right company.

That night, I called my best friend, whom I’d known since my freshman year of college, and I almost cried. “I might have made a mistake taking this job,” I told her. She listened, reminded me why I had worked so hard to get there and convinced me to stay the course. I’m so glad she did.

At the time, I wasn’t thinking about leadership philosophy. I was simply trying to learn the business and prove that I deserved the opportunity I’d been given. Eventually, she left the company, and I remember feeling an enormous sense of relief. I could finally focus on becoming a great sales representative instead of worrying about what kind of day my boss was having. Looking back, she was my first up-close lesson in DUD leadership.

The Promises I Made to Myself

Years later, when I began managing people myself, I thought about that car ride more often than I’d like to admit. I realized that employees should never have to spend their energy managing their boss’s moods. They should be spending that energy doing their jobs, developing their skills and taking care of their customers. As my career grew and I eventually led organizations of more than 1,300 people, I came to appreciate just how much influence a boss has over someone’s working life. One conversation, or one long car ride, can leave a person energized or ready to quit.

So I made a few promises to myself. I would be the same leader every day, so no one on my team would ever have to check my mood before asking a question. I would criticize in private and praise in public, and I wouldn’t let a day go by without noticing what someone was doing well. And I would talk about the company the way I wanted my team to talk about it, because negativity from the top spreads faster than almost anything else in an organization.

That doesn’t mean leaders should avoid difficult conversations. Good leaders hold people accountable, address performance problems and sometimes make unpopular decisions. Being liked isn’t the goal, and a leader who avoids every hard conversation isn’t doing anyone any favors. But there’s a world of difference between being demanding and being demeaning.

One helps people grow. The other makes them question whether they belong.

I wouldn’t want to repeat that first year at Upjohn, but I wouldn’t trade what it taught me, either. That experience, and especially that long day in the car, helped shape the kind of WOW leader I wanted to become. Sometimes the worst boss you ever have turns out to be one of your best teachers, because she shows you exactly what not to do when it’s your turn to lead.

What did a bad boss teach you about leadership?

–Sheri Staak