Learn English – Difference between ‘He always worked there ‘ and ‘He was always working there’

If you wish to express the idea that you used to do something "back then", or "when I was a kid", or that something used to happen or used to be the case, you can use the past progressive:

People were going to bed much earlier in the days before the electric light.

Before I realized that I could predict the future, I was earning a regular salary. Now I play the stock market.

As a heroin addict, he was living in a bad dream. But now he's clean.

In preparation for the bar exam, she was studying late into the night.

If you want to express the simpler idea that something happened at a point in time in the past, you can use the simple past:

It was New Year's Eve, so she stayed up past her normal bedtime.

The farmer mowed his field of hay.

He talked at length about particle physics.

Those same sentences can be recast into the past progressive. In doing so, the action is presented as an ongoing action.

It was New Year's Eve, so she was staying up past her normal bedtime.

The farmer was mowing his field of hay.

He was talking at length about particle physics.

The imperfect merely describes something that was ongoing at some past time.

I worked in New York two years ago. [all we know is that the working was at that point in the past]

I was working in New York two years ago. [The activity of working was ongoing at the time, two years ago.]. These are often sentences that imply something else that occurs after a when clause even if not explicitly stated: I was working in New York two years ago when my boss fired me.

Both are past, both are finished. Neither addresses when you started or stopped working. One says you had an ongoing activity and the other merely said you performed that activity two years ago.