Personalization works best when it feels helpful, not like someone is watching your every move. Using a person's first name in an email or recommending a product based on what they already bought feels natural. But when ads follow someone around the internet or reference very specific behavior, it starts to feel uncomfortable. The balance is to use data in ways that make the experience better for the user, not just more targeted for you. Transparency also helps. When people know why they are seeing certain messages, they trust it more. How far do you think personalization should go before it becomes uncomfortable?