Someone is struggling to get out of bed, and the poem never pretends there's a good reason to. The speaker admits that food, water and a trip to the bathroom are about all that could pull them up, and even those feel like chores. The phrase "liquid head" suggests a mind that is foggy and formless, unable to hold a clear thought.
The second stanza gives the feeling its strangest image: a "light heavy weight" sitting in an "aching empty chest." It's a contradiction, but it fits. The speaker feels both weighed down and hollow. They seem resigned to waiting, to being "down and out with the rest," which hints that they aren't alone in feeling this way.
The last stanza is the saddest. The speaker shrugs it off as nothing new, then says to be glad it only happens to them. The final line, "easier to look but not see," suggests that other people may glance at their pain without noticing it. The mood is flat, tired and quietly lonely.