The speaker starts with something familiar, window shopping, and turns it into a way of seeing a whole life. Each window holds a stage of the past: rattles and diapers from babyhood, macaroni necklaces and birthday parties from childhood, candy hearts and puppy-love heartbreak, then photos of a high school sweetheart. Looking at them, the speaker feels both fondness and a little ache, since the long nights and pains are remembered alongside the good times.
Then the poem turns toward a new window, the future. The mood shifts to a mix of excitement, nervousness, and queasy uncertainty. Leaving the "familar past" for an "unforgiving, unknown future" is scary, and the speaker admits it. Still, the ending is encouraging. The speaker urges the reader to keep the good memories, but to move forward anyway, because without the future there is nothing new to cherish. Taking even one peek is worth it. The overall tone is nostalgic, gentle, and hopeful, like advice from a friend standing at the edge of a big change.