The notion of staying longer after work to be more productive is a fallacy that will keep you chasing the clock.

To be most productive, you need to leave work on time. To sustain the habit of leaving work on time, start with a small step.

As the new year begins, decide that, say, every Tuesday you will stop working on time, without taking extra work home with you.

After freeing up Tuesdays for an entire month, add Thursdays. In another month, add Mondays, and in the fourth month, add Wednesdays. I won't mention Fridays because I'm assuming that there's no way you work late on Friday (or do you?)!