This is what I've cobbled together so far from different sources:

WORKING MAN

CHORUS: It's a working man I am
And I've been down underground
And I swear to God if I ever see the sun
Or for any length of time
I can hold it in my mind
I never again will go down underground

At the age of sixteen years
With my father close to tears
As he vowed never again to send his son
To the dark recess of the mine
Where you age before your time
And the coal dust lies heavy on your lungs

At the age of 16 years
Oh, he quarrels with his peers
Who vowed they'd never see another one
In the dark recess of the mines
Where you age before your time
And the coal dust lies heavy on your lungs

At the age of 64
Oh, he'll greet you at the door
And he'll gently lead you by the arm
Through the dark recess of the mines
Oh he'll take you back in time
And he'll tell you of the hardships that were had

At the age of sixty-five
I pray to God I'm still alive
And the wheels above the mine no longer wind
And they've finally closed the hole
Where for years we clawed for coal
And never again will we go down underground