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One-minute behavior change interventions might seem too brief to matter. Could something so short really help people build healthier routines? This work explores this question through two studies examining how ultra-brief prompts might encourage meaningful actions in daily life. In a formative study, we explored how participants engaged with one-minute prompts across four domains: physical activity, eating, screen use, and mental well-being. This revealed two common design approaches: Immediate Action prompts (simple, directive tasks) and Reflection-First prompts (self-awareness before action). We then conducted a 14-day, within-subjects study comparing these two flows with 28 participants. Surprisingly, most participants did not notice differences in structure -- but responded positively when prompts felt timely, relevant, or emotionally supportive. Engagement was not shaped by flow type, but by content fit, tone, and momentary readiness. Participants also co-designed messages, favoring those with step-by-step guidance, personal meaning, or sensory detail. These results suggest that one-minute interventions, while easily dismissed, may serve as meaningful gateways into healthier routines -- if designed to feel helpful in the moment.