Methods for operating a portable electronic device to conduct a mobile payment transaction at a merchant terminal are provided. The electronic device may verify that the current user of the device is indeed the authorized owner by requiring the current user to enter a passcode. If the user is able to provide the correct passcode, the device is only partly ready to conduct a mobile payment. In order for the user to fully activate the payment function, the user may have to supply a predetermined payment activation input such as a double button press that notifies the device that the user intends to perform a financial transaction in the immediate future. The device may subsequently activate a payment applet for a predetermined period of time during which the user may hold the device within a field of the merchant terminal to complete a near field communications based mobile payment transaction.