Tread water

"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. "