In the song, the speaker personifies winter as a personified figure who is described as "thou winter wind" and "thou rawest wind that ever yet blew." The speaker uses vivid language to describe the harsh effects of winter, such as the wind that "bites" and "blows" and the "frosty" air that "nips" the speaker's "fingertips." The speaker also describes the negative effects of winter on nature, such as how the trees are "bare" and the "flowers are gone."
The speaker's tone in the song is one of sadness and regret, and the overall message of the song is that winter is a time of hardship and suffering. While there is no explicit mention of the forest in the song, it is implied that the speaker is in the forest, as they mention trees. The speaker does not express any joy or acceptance of the challenges of winter, but rather longs for the return of spring, when the weather will be more pleasant and nature will be more beautiful.
Therefore, the song "Blow, Thou Winter Wind" does not justify cheerful acceptance of rigors in the forest. Instead, it laments the harshness of winter and expresses a longing for the return of spring.