put in a hard day at work
To work for a full day doing something that is physically or mentally exhausting. After putting in a hard day at work, the only thing I want to do is sit back on my sofa and relax. Quit complaining—you've never put in a hard day at work in your life.
put in a hard day at work
and put in a hard day's workFig. to work very hard at one's job. I put in a hard day at work at the office, and now I want to be left alone to rest.