And I made a great number of huge mistakes. I did some important things right too, but my missteps were legendary (at least in my own mind). When I look back on my 30 years of working, and the careers of the hundreds of folks I train, coach and teach, five blunders stand out from all the rest as the most negative, damaging, and irreversible in your career and professional life.

I had an 18-year corporate career in publishing and marketing that was highly successful on the outside, but on the inside, it was not. I rose to the level of Vice President and managed multimillion-dollar budgets and global initiatives, but throughout my career, I faced a number of excruciating experiences of gender discrimination, sexual harassment, work-life balance failures, chronic illness and exhaustion, being sabotaged and betrayed by colleagues, and the continual nagging feeling that I was meant for different work (but simply couldn’t figure out what it was –here’s more on that story)….

The 5 things you should never do at work are:

1. Speak, behave or quit out of rage or revenge

Most people spend more hours at work than anywhere else, so it’s normal and expected that we will experience the full gamut of emotions while engaged in our work. I’m all for bringing our whole selves to work as well, and being as authentic, honest, and transparent as humanly possible at our jobs. That said, I’ve watched the inevitable destruction of losing control of your emotions and acting out rashly and impulsively from rage or despair.

2. Backstab your colleagues

I’m astounded at how many people today feel completely comfortable ridiculing, disparaging or undermining their colleagues, co-workers and even their friends. I used to be that kind of person – talking behind someone’s back if I felt they were behaving poorly, meanly, or less than professionally….

3. Lie

We tell lies most often when we think that the truth will hurt us somehow, or when we want to avoid facing the consequences of our truth. The problem with lying is two-fold: 1) When you tell yourself you’re not capable of facing reality or dealing with the consequences, you make yourself right – you’ll grow less powerful, capable, bold, respectable, and trustworthy over time, and 2) the lies you tell must be perpetuated, which is exhausting and drains you from vital energy you need to reach your fullest potential.

4. Proclaim that you’re miserable

Just the other day, I was talking to a former client who had marched into her boss’s office that week and shared that she was miserable at work and volunteered for a severance package. I’ve done that myself – been so unhappy at work that I put my hand up for a package. I didn’t get it, and neither did my client….

5. Burn bridges

Literally the biggest lesson I’ve learned in business is that success is all about relationships. It’s truly about whom you know, and how they feel and think about you (and how you make them feel). I’m not saying that your amazing talent and skill aren’t important. Of course they are. I am saying that we don’t thrive and succeed alone….

Every single one of your relationships is vitally important to you and your future, so craft them with care. Avoid people you don’t trust or like, but don’t burn bridges.