slog (one's) guts out
To put a great amount of effort into something; to work very hard at something. I slogged my guts out for a few years as a court messenger for a legal firm while I finished up my law degree, and they eventually offered me a job as an attorney. There's nothing more disheartening than to slog your guts out on an assignment, only for the computer to crash and delete all your work.
slog/sweat/work your ˈguts out
(informal) work very hard: I’ve slogged my guts out digging this ditch, and I’m completely exhausted.You sweat your guts out all your life and what do you get when you retire? Next to nothing. OPPOSITE: not do a stroke (of work)