When I first began representing Colorado in Congress during the late 1990s, the world looked very different. Less than three years before I was elected to the House of Representatives, Congress had passed the Defense of Marriage Act, legislation that banned marriage for gay couples at the federal level. More than 80 percent of the Senate and House voted for this law. At the time, no state allowed gay couples to publicly affirm their commitment to each other and their communities through civil unions or marriage.

Today, we face a very different world. Our country and leaders have undergone a stunning transformation regarding this issue — and my own thinking has evolved as well. As a moderate Western senator who supports allowing committed gay couples to publicly affirm their relationships and responsibilities through marriage, I believe my journey illustrates three important lessons about how we can make progress in this country, far beyond the marriage debate.

First, good-faith re-examination of a position you’ve held in the past should be seen as a virtue, not a vice. Like most Americans, there was a point when I struggled with the idea of allowing gay couples to marry. I thought perhaps there was another way of resolving the issue, such as civil unions, that would satisfy both sides and avoid a major national argument.

But as time went on, I began to realize that gay couples just want to make the same promise of commitment and fidelity that my wife and I made so many years ago. I thought about my own wedding day — one of the happiest of my life — and I began to think that there is no substitute for the unique, public promises I made that day in front of our family, friends and community. And as I talked about the issue with my children and learned how open they were to marriage equality, I realized that allowing two loving, committed people of the same gender to make a promise of lifetime fidelity complemented my own beliefs surrounding the importance of family.

But in this age of “flip-flopping,” some people warned me that talking publicly about my personal transformation might be used against me. Despite this concern, I felt I needed to step up, and in August 2011, I announced my full support for same-sex marriage. At the time, I was only the 19th U.S. senator to do so — not many more than the 14 senators who had voted against DOMA when it passed 15 years earlier. And although I hail from a moderate, purple swing state, Coloradans have not punished me for changing my mind. If anything, they have supported my sincere reconsideration and honesty.