Will you be pissed or hugely inconvenienced if you lose it?
If you said yes, put that item in the neck pouch. Wear the neck pouch under your shirt or sweater.
I think I found the right product for this:
This neck pouch lanyard does not contain a slash-proof wire, but the idea is security through obscurity – the thief shouldn’t even see this pouch. With RFID blocking material, information stored in your passport and credit card smart chips is safe.
Read reviews and check prices: Pacsafe Luggage Rfidsafe 75 Neck Pouch