Memorizing a poem brings the text closer to you. Once you've internalized it, you can carry it with you wherever you go. It becomes like a little, secular prayer you can hold close to your heart and return to whenever you need it.
If you're looking for one to start with, here's an excerpt of "The Call of the Wild" by Robert W. Service:
Let us probe the silent places, let us seek what luck betide us;
Let us journey to a lonely land I know.
There's a whisper on the night-wind, there's a star agleam to guide us,
And the wild is calling, calling . . . . let us go.