"Follow your passion," without any other qualifying parameters, can be bad advice. And sometimes, our passions might be so obscure and unique that there's no possibility of making a living from it.
But following your passion goes beyond your career. It leads, ultimately, to a life well lived. I'm not passionate about my day job, but I am passionate about the lifestyle it allows me. I follow my passions on my own time, and they have lead me to all the best experiences of my life so far.