In the poem "Ulysses" by Alfred Lord Tennyson, Ullyses returns to his home after a 10 year voyage and many adventures. Considering his future as an older man, he realises that he is now facing a different kind of battle, not against enemies, but against the inevitable process of aging:
Though much is taken, much abides; and though
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are,
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.