How am I expected to carry a key fob equivalent of a smart card attached to my key ring?

A number of wireless smart card issuers is promoting so-called payments tags or key fobs - that's a small wireless device which can be used in place of a wireless payment card or wireless transport card and it's designed so it looks like it should be attached to a key ring. Mastercard PayPass is one example of smart card accompanied with such device. You simply bring such device close to a POS terminal and it completes a payment transaction the same way if it were a wireless payment card.

How do I carry it around?

If I attach it to my key ring then I have to take my entire key ring out of my bag or pocket every time I need to confirm a payment on a POS terminal. The more often I take my key ring out the more it's likely that I get it lost of forgotten somewhere. If I do the same with a transport card equivalent every time I need to enter a bus or metro during a rush hour I risk having my key ring dropped in the middle of the crowd or maybe even on an escalator.

So it looks like attaching such device to a key ring is not very wise. Carrying it standalone isn't very practical too because the device is rather small and hard to find inside a bag or pocket.

How is this thing supposed to be carried such that its holder doesn't risk losing his keys all the time?