Why does the poet say that he is done with apple picking in "After Apple Picking"?

While on the surface, the narrator of Robert Frost's "After Apple Picking" only has one reason for being done with apple picking, when looked at symbolically, there may be another reason entirely for the cessation of the work. The poem starts with the narrator suggesting that there is more work to be done. The ladder is still in the tree, a barrel is left unfilled, and there are still apples hanging on the boughs. However, in lines 6–9, the narrator reveals that the work will remain unfinished:

But I am done with apple-picking now.
Essence of winter sleep is on the night,
The scent of apples: I am drowsing off.
I cannot rub the strangeness from my sight

On the surface, the narrator is simply tired. The night is coming on, and they are growing drowsy. Their body aches and their vision is growing "strange," suggesting they have been working for a long time and need to rest. On a symbolic level, this can be seen to represent death, particularly given the use of "winter sleep" and "strangeness" of "sight."
Further on in the poem, the use of the end of apple picking as a metaphor for death continues, as the narrator states:

For I have had too much
Of apple-picking: I am overtired
Of the great harvest I myself desired.
There were ten thousand thousand fruit to touch,
Cherish in hand, lift down, and not let fall.
For all
That struck the earth,
No matter if not bruised or spiked with stubble,
Went surely to the cider-apple heap
As of no worth. (27–36)

Here, the "great harvest" can be seen to represent a full, contented existence, and the narrator doesn't feel they have attained such a life. This perspective can also be seen in the despondent feeling within the final group of lines above. No matter what one has done in life, "all / That struck the earth . . . Went surely to the cider-apple heap / As of no worth."Be it literal or figurative, the narrator's fatigue is the catalyst for the will to be done with apple picking.