Tiredness is something that we experience in life.
It may be physical tiredness, it may be mental tiredness, or it may just be fatigue and we might not even be sure if it is physical or mental.
And to add on to the question, could it even be spiritual tiredness?
If we are spiritually tired, then no doubt physical and mental fatigue will set in.
If our hearts are burdened with anxieties and worries, if our hearts are not at rest, then life is really a tiresome journey.
The 1st reading tells us to do this: Lift up your eyes and look. Who made these stars if not He who drills them like an army, calling each by name? So mighty is His power, so great his strength, that not one fails to answer.
The energy that we see in nature - the sun, the wind, the sea - are impressive and we know it is God who created them.
We too are created by God, and we are given power to put out wings like eagles, but we get tired out and weary by the many cares in life.
And when we fail to obey God and when we don't live our lives according to His will, then spiritual fatigue sets in followed by mental and physical tiredness.
The season of Advent calls us to heed the call of Jesus to come to Him, and to learn to accept and carry the crosses of our lives.
The cross may seem burdensome and difficult, but in it we will find rest for our souls and we will receive the strength to put out wings like eagles and live life joyfully.