Like many members of her generation, Elizabeth Warren earned a college degree without taking on crippling student debt.

But in a CNN op-ed published Monday, Warren zooms in on how the opportunities she was given no longer exist for students today.

"Growing up, I knew I wanted to be a public school teacher. But for that you needed a college degree — and to get a college degree you needed money my family didn't have. Still, I figured it out. I got a scholarship and headed off to George Washington University," she writes.

When she was 19, Warren dropped out of college to get married and took a job answering phones. But she still dreamed of being a teacher.

"I heard about the University of Houston. It was a public four-year college just 40 minutes away and tuition was just $50 a semester — something I could afford on a part-time waitressing salary," she writes. "I got my degree and went on to become a teacher for students with speech and learning disabilities. I got to live my dream.

"I got to become a teacher, a law school professor, a United States senator and now a candidate for president because higher education opened a million doors for me," writes Warren. "But the chances I got don't exist anymore."

In the years since Warren attended college for $50 a semester, the cost of college has skyrocketed. Today, tuition at the University of Houston can range from $5,317 to $15,027 per semester, depending on factors such as residency status and degree program — and that's without considering costs like fees, room and board.

According to Discover, the average cost of college for full-time undergraduate students has increased 143% since 1963. The financial services company estimates that during the 1963-1964 school year, the average student paid the equivalent of $9,818, in 2017 dollars, for tuition, fees, room and board. During the 2016-2017 school year, students paid approximately $23,091 to cover the same costs.

These costs have increased fastest at public four-year universities like the University of Houston. According to the College Board's 2018 Trends in College Pricing Report, from 1988 to 2018, sticker prices doubled at public two-year and private non-profit four-year schools, but tripled at public four-year schools.

And while Warren was able to pay her tuition by working part-time as a waitress, students today are unlikely to do the same. Discover estimates that in 1963, students could work a full-time minimum wage job for six months in order to cover one year of tuition, fees, room and board. In 2016, students would need to work full-time for 18 months.