Give students the texts (or let them choose a paragraph from any English text they have). For higher-level students, one of the texts is more hopeful, and the second one is more melancholic. With higher-level students, you can also select the texts from any authentic sources.
Instruct students to read the text once. Circle/underline words or short phrases that resonate with you. Cross out (or digitally black out) everything else. Encourage students to trust their instincts, there's no wrong way to do this, really. Thinking about the mood/feeling they want to create first may help. Focus on feeling rather than perfect grammar. With higher-level students, you may want to introduce even more challenges by prompting them to create more abstract poems, a poem with very few words, or go for unexpected word choices.