In this poem, Ulysses recalls his past when he was a man of action. Now, in his older age, he laments the fact that he has become a man of inaction. He is unsatisfied with staying at home with his wife and being a ruler. He craves a life of adventure and this poem expresses this craving and Ulysses' frustration with settling down and getting older. Ulysses claims that to be inactive is to become useless: 

How dull it is to pause, to make an end, 
To rust unburnish'd, not to shine in use! 

In the second section, Ulysses adds that his son, Telemachus, is more suited to the settled lifestyle of a ruler whereas he, Ulysses, is more suited to a life of adventure. 

In the last section of the poem, Ulysses tries to rally the troops (and himself) to seek adventure (and action) once again, despite their ages. He acknowledges that he and his men are old. Ulysses here shows his adventurous spirit but also his desperation. He wants at least one more adventure before "the end." 

Death closes all: but something ere the end,
Some work of noble note, may yet be done, 

On one hand, Ulysses is neglecting his wife and social duties. On the other hand, Ulysses shows some spirit in his old age in seeking to be more active; albeit by leaving his wife at home.