Preocupar means "to worry" or "to be concerned." While it might seem like a common word, its placement at the beginning of the song sets a melancholic tone.
The singer states, "En vez de una sonrisa, me empiezo a preocupar" (Instead of a smile, I start to worry). This immediately tells the listener that the song is about longing and sadness, making it an interesting and emotionally resonant word choice to draw users in.
Julión Álvarez Y Su Norteño Banda's song "Quiero" is a heartfelt journey through the mind of someone deeply missing a past love. From the moment the day begins, it's clear things aren't right: "De que abro los ojos ya mi día pinta mal" [From the moment I open my eyes, my day looks bad]. Instead of a smile, worry takes over. He can't forget her, and her "Besos siguen andando en mi piel" [Kisses are still walking on my skin].
The song is a list of all the things he wants but can't have. He longs to see her face again, "esa que ponías conmigo en la cama" [that one you used to make with me in bed], and to relive the "magia" [magic] they shared. He misses her comfort, saying "Quiero quitarme este frío y tú siempre has sido muy buena pa' eso" [I want to get rid of this cold and you've always been very good at that]. But there's a big "pero" [but] – all these desires are just wishes. He realizes, "Quiero tantas cosas que no se van a poder" [I want so many things that won't be possible], and can only make them real "solo en mi mente" [only in my mind]. The contrast between what he wants and what he has is stark, especially when he wishes for "otro 14 de febrero junto a ti" [another February 14th with you], but all he gets is "un diciembre sin ti" [a December without you].