Passion is what drives people in life. The passion that has been lost is his drive or determination to succeed in life. Some guy asks Aesop if he can notice that he seems to have lost it. Aes says he can see it, but only when he gets past him. You only notice that people aren’t working hard when you are working harder than them. His bit of lost passion is in front of him, hence why he could only see it when he passed him.
This video is processing – it'll appear automatically when it's done.