For me, respect isn't something that comes because of age, seniority or gender, but because of the quality of your ideas and the quality of your work.

It was the early 1970s and I was a newly-elected member of the Dutch Parliament. It was an overwhelming place to be: a male-dominated institution, with much history, and many conventions written and unwritten. Yet also a very exciting place: I was filled with awe at the opportunity to change things for the better, and knew that's what I had been elected to do.

I remember one debate in particular, very early on in my career. I was around 30 years old, just about to make my maiden speech. One older, male member of parliament spoke. It didn't sound right to me: full of claims I knew to be untrue. I was uncomfortable hearing him going unquestioned. Staying quiet and accepting nonsense wasn't why I was in politics. But no one else seemed to want to challenge him, and I was a newcomer. What was the right thing to do?

In the end I couldn't bear it any longer: I intervened to challenge him, and pointed out exactly why he was wrong on his facts and figures. The response I got from him was, to say the least, dismissive. He didn't address my criticisms, but just carried on, stopping only to comment on my appearance, “Doesn’t she look nice and dress well?”

That didn't make me feel too good. He no doubt felt he was being flattering, when in fact it was merely belittling. And I knew I had to intervene again. This time I matched his comment about my clothes, and I spoke out about his own: He was wearing an awful suit, and I came out and said so. Well, I thought, if he felt that talking about how people looked was appropriate in a parliamentary debate, then so be it – but he shouldn't think he could get away with it.

Afterwards, my friends and colleagues asked me how I could have done such a thing – he was, they told me, a long-standing member of parliament, established and “respected.” That was when I knew I'd done the right thing. For me, respect isn't something that comes because of age, seniority, or gender, but because of the quality of your ideas and the quality of your work. If seniority and respect was the only reason why others didn't speak out, I was proud to be the one who did.

In the short term, I think some people found it shocking that I was prepared to be so assertive so early on in my career. And at the time even I found it uncertain and frightening. But, looking back, I know it's the right thing to have done. My colleagues came to realize why I did what I did – and in turn to recognize and respect me for standing up for what I believe in. It's a philosophy I've carried with me.

Forty years later, I've enjoyed a varied career: from government minister, to board-level in the private sector, to University President; now I'm Vice-President of the European Commission. But in each of those jobs, I've kept that same spirit, and always stood up for same values. I'm glad I did it right from the start.