Act as a seasoned e-commerce copywriter with 5+ years of experience crafting high-converting upsell emails. Write a persuasive upsell email for [PRODUCT_NAME], targeting customers who recently purchased [RELATED_PRODUCT]. The email should highlight [KEY_BENEFIT_1], [KEY_BENEFIT_2], and [KEY_BENEFIT_3] of the upsell product, while creating urgency with a limited-time offer. Use a friendly yet persuasive tone, and include a clear CTA. Structure the email with: 1) A relatable opening hook, 2) A smooth transition into the upsell, 3) Bullet points emphasizing value, 4) Social proof (e.g., '[NUMBER] happy customers'), and 5) A time-sensitive discount (e.g., '[X]% off for the next [Y] hours'). Keep it under 150 words.