It’s actually all about the data about you.
Acxiom is one of the big players in aggregating data about users, their habits, preferences, purchasing patterns, and yes, probably right down to what time of day or night you like to browse, by topic, etc.
Which means the more you can avoid telling the entire universe all of that information, you can at least maintain a little privacy in your profile. Amazon knows you better than you know yourself: local warehouses are filled with things that Amazon already knows you will order before you know it yourself. Then amazingly (amazonly?) that item is going to be delivered in 2 hours ! At most, same day. Don’t be surprised (you really aren’t, are you?).
What can you do today? Follow the guide at the top menu entitled “What Can I Do Right Now?”.