A woman goes for a walk in the park because she hopes it will help, and for a while it does. Then a running figure, a soft voice and an outstretched hand turn into a nightmare in her head. She freezes, imagines the worst, and walks away feeling she has outsmarted a trap. Back home, she decides the park is full of creeps.
The twist comes when the speaker admits it was all imagined. The "monster" was a jogger, the "soft voice" was someone checking if she was okay, and the hand was meant to help her up. The real "creep" is the speaker herself, who has been reading kindness as threat.
The mood shifts from tense and frightening to quietly rueful. The short, jumpy lines mimic racing panic, and the closing repetition of "Overthinking" sounds tired and a little embarrassed. Judging by the final lines, the speaker is looking back at months of anxious thinking and laughing at herself, though not without some pain.