What are the key differences between a ritual and a routine? How does one empower us while the other leaves us dull and unsatisfied?

I just finished reading the latest edition of Psychology Today and came across a very interesting experiment. The results showed that students who were told that nervousness would improve performance ended up scoring better on their Graduate Record Exam (GRE) than students who were told nothing at all.
The study (PDF download) was done by [...]