How do you ask for a borrowed item back without making it weird?

A borrowed book, charger, or kitchen tool can remain at someone else's home long after both people expected. Sometimes it has simply been forgotten. Sometimes the owner keeps waiting for a natural moment to mention it, while quietly needing it back. The longer it goes on, the more formal the request starts to sound.

What is an easy way to ask without turning a small thing into a conflict? Would agreeing on a return date when lending solve most of this? Interested in practical wording and boundaries, especially when someone is generous about borrowing but less organized about returning.