The speaker begins with a blunt admission: they are weary with themselves. It isn't tiredness from work or a long day, but a worn-out feeling about their own company, their own thoughts. Then the poem turns, as the title promises, outward. The speaker looks at the fields instead, and the poem becomes a short list of things seen.
The phrase "their leased light" is the strangest and most interesting moment. Light is something the fields only borrow, never own, and the word suggests that everything here is temporary, on loan. That may quietly echo the speaker's own sense of being passing and small. The last image, a fox at play, is simple and lively. The fox has no self-consciousness at all.
The mood is quiet, a little melancholy, but also relieved. Nothing is solved. The speaker just gets a break from themselves by paying attention to the world, and the poem lets that small mercy stand without explaining it.