Four short lines carry a feeling that's hard to put into words, and the poem knows it. The speaker describes being weighed down, as if something heavy has settled on them and won't lift. The title, "Full," is interesting here. You might expect it to mean satisfied, but it seems to mean the opposite: stuffed with feeling, overloaded, with no room left to move.
The line breaks help. "Can't move" and "Don't want to" sit on separate lines, so the pause between them feels like a sigh. The speaker isn't only unable to act, they've also lost the wish to. That small shift makes the heaviness feel deeper than simple tiredness.
The last line admits to "lots of regret" that can't be expressed. We don't learn what the regret is about, and that silence is the point. The mood is quiet, stuck, and sad, like someone sitting still with feelings too big to say out loud.