Tired, fatigued or exhausted

This makes a lot sense to me:

...[T]iredness, fatigue and exhaustion ...represent various points on an energy continuum. The amount of energy a person has influences how easily he can adapt to stress that comes his way. Individuals who are tired still have a fair bit of energy, so although they may feel forgetful, and impatient, and experience gradual heaviness or weakness in muscles following work, this is often alleviated by rest. Fatigue, on the other hand, is characterized by difficulty concentrating, anxiety, a gradual decrease in stamina, difficulty sleeping, increased sensitivity to light and the limiting of social activities once viewed as important. Individuals with exhaustion report frank confusion that resembles delirium, emotional numbness, sudden loss of energy, difficulty both in staying awake and in sleeping and complete social withdrawal.

"It is important to recognize the difference between tiredness and fatigue, because fatigue is a marker that the body is not able to keep up...The onset of the manifestations of fatigue, particularly if these are not normal states for you, should be taken seriously."

Failing to understand the distinctions between tiredness, fatigue and exhaustion could result in the use of inappropriate interventions that inadvertently promote fatigue and exhaustion...While exercise appears to help those who are tired, it may decrease the ability to adapt in individuals experiencing fatigue and exhaustion. Long-term use of caffeine and other stimulants should also be avoided by people experiencing fatigue and exhaustion, as these substances "fool" the body into thinking it has more energy available than it really does.

The bottom line is that feeling a bit tired(not bored) might be a good thing, take a good rest you will be recharged and ready to go again. Fatigue is a warning signal that your body tells you to slow down a bit, and exhaustion is like the ultimatum from your body.