Modern science has largely vindicated that thinking, but don't tell your humors that. The fever itself isn't bad, especially if it doesn't climb past temperatures dangerous to your health and well-being, usually around 40° C, or 104˚ F.
Researchers like Dr. A. Sahib Mehdi El-Radhi have pointed out that the decision-making behind administering antipyretics (aka fever-reducing drugs) is often grounded in what physicians call "fever phobia" rather than science. "There is still a significant contrast between the current concept and practice, and the scientific evidence," he wrote in a 2012 paper discussing that disconnect. "The accumulated data now suggest that fever has a protective role in promoting host defence against infection, rather than being a passive by-product. A moderate fever (less than 40° C [or 104˚ F]) is beneficial."
The American Academy of Pediatrics agrees with this, saying fevers can help children fight off infections.
OK, but 104˚ F still kinda sucks...
Admittedly, yes -- as do headaches, sweating, shivering, fatigue, weakness, aches, loss of appetite, and other fever symptoms you might get in addition to a high temperature. If you really want to fight off a fever and get back to work, your best courses of action are the following: