Out of the night that covers me,
Black as the pit from pole to pole,
I thank whatever gods may be
For my unconquerable soul.
In the fell clutch of circumstance
I have not winced nor cried aloud.
Under the bludgeonings of chance
My head is bloody, but unbowed.
Beyond this place of wrath and tears
Looms but the Horror of the shade,
And yet the menace of the years
The road gets bumpy from time to time and even though these challenges can rough you up a bit, the speaker still stands with his head held high, not letting anything get in his way. 
 Words like  clutch, winced, cried, unbowed  —a  semantic field  of words relating to inflicted physical pain — would have had a stark personal resonance for Henley, who suffered from  tuberculosis of the bone. See his  biographical sketch  at Victorian Web. 
 One commentator saw the image of ‘bludgeonings’ and ‘bloody head’ as reminiscent of a boxer raining blows. 
 Note the three  plosive  ‘b’s to give emphasis, especially if the poem is read aloud.
Invictus