"In the middle" of a time span – will "middle" work? Better ideas?

I am translating a German text into English.

It contains a sentence that translates roughly to

In the middle of life, you stand alone.

I'm unsure about "middle" here, and can't think of a more fitting substitute. "Life" is related to the time span of a single human life. Therefore, "center" is out of the question of course. Or is it?

Would you use "middle" in this sentence?

Do you have a better idea?

A similar phrase in English would be middle age:

Middle age is the period of age beyond young adulthood but before the onset of old age ... usually considered to occur approximately between the ages of 40 and 60

At middle age, you stand alone.

Note that this phrase does indicate a specific time period in a person's life. If you are looking to describe everything between birth and death, a more correct sentence would be:

In life, you stand alone.

If the intended time frame is from the end of childhood to the beginning of old age, I would go with:

As an adult, you stand alone.

Or:

In adulthood, you stand alone.

Not part of your question, but I wonder about the intended meaning of "you stand alone". I don't know the whole context, but as it stands, what is conveyed leans towards "you are on your own, there is no-one with you". If what you are trying to say is "you are independent and no longer dependent on others for your identity", you might want to consider something like "you are your own person", "you stand on your own two feet"...

Just a thought.