"to tread water" is an idiom, that means: To put a lot of time and effort into something, but not get much of a result, or get a better result that you might have been getting previously.
Guy 1 : "Man, all day I've been sitting here thinking, all I do is tread water lately.... "
Guy 2: " Why's that? "
Guy 1: " I don't know, maybe I haven't been pushing myself hard enough lately. Maybe I need to go back to my roots, and just grind like I used to. "
Telling somebody to go away. Also said to unimportant people in your life when they try to talk to you. Or how you feel when you feel that you can't move forward.
guy1: Why haven't got a new girl friend guy2: because I can 't move on
Guy1: she was 5years ago...
guy2: I know
Guy1: Ugh, you love to tread water