Confusing intensity and passion is a common mistake. Intensity is external; passion invokes something inside you. Passion is a call-and-response with your soul. It’s not just adrenaline.

– Po Bronson makes a useful distinction in his book What Should I Do with My Life? (my review). It’s easy to look back at intense, adrenaline-driven times in your career and feel nostalgia for the clarity of focus, but it doesn’t necessarily mean what you were doing was your passion.