Antonyms for the phrase "calling it a day" include "continuing on," "not quitting," and "persisting." These words suggest that instead of stopping work or other activities, one should keep going and push through any challenges or obstacles that may arise. Other antonyms may include phrases such as "staying the course," "unwilling to give up," or "doggedly pursuing" one's goals or objectives. Ultimately, the antonyms for "calling it a day" encourage people to stay motivated, persist despite setbacks, and continue striving toward success in their endeavors, whatever they may be.