Why would it be difficult to depress the button that locks the gearshift in Park?

the car has a cable between the key and the transmission shifter. if this cable is worn it can be very difficult to shift from park, and will only get worse. I just disconnected mine, but you will probably want to get a new one installed at any auto shop. In our 92 Camry, my brake switch had gone bad. We had not noticed the rear light out, but I had extreme problems shifting out of park to either drive or reverse. Once the switch was replaced, smooth sailing! The car was not sensing that the brake was depressed to release the gearshift button.