How to find a potential career path while in college

Digital Marketing Director John McElhenney mentions Thomas Moore in his post, "Love Money Ambition: Finding Your Sweet Spot and Career". In his piece about college and career choices, McElhenney writes:

Here's what you either learn or don't learn at college: the passion for learning something new, and the ability to recognize that passion and follow it along to some conclusion. This is different from "follow your bliss" self-help kind of following. The follow is about YOUR PASSION. In college you finally have the ability to follow the ideas, philosophies, and [potentially] career path that will set the next 30+ years of your future working-life in motion. 

In Thomas Moore's Care of the Soul, he talks about listening to where your heart gets it's greatest excitement. When you talk to others, what topics and ideas really get your blood boiling. Perhaps that is where your soul will be most satisfied." 

He describes fulfilling his desire to be a writer while working in advertising and marketing.