54. Passion.

What I really should have titled this is "That spark in the eye of a 60-year-old professor when he hears people discuss his field of studies", but I figured that might have been a bit too verbose. As I stress, lose motivation and get frustrated with the every-day demands of grad school, it is inspirational and exciting to see people who genuinely love what they do even after thirty years of doing it. It's not just a job, it's a passion. Talking with him and arguing methodology with brilliant students left me in awe, inspired to one day achieve half of what they have, and comforted that there is light at the end of the tunnel and people to guide me in the right direction.