Press on pressure sensor once, turn on LED for 6 seconds
Sensors which give a range of outputs need to have their outputs processed using a technique called hysteresis.  That is, normally, the turn on threshold is higher then the turn off threshold.  

For example, the thermostat in your home uses hysteresis when controlling your HVAC system.  Otherwise your thermostat would constantly be turning on and off your HVAC system likely causing an early failure.

Here is a stackexchange Arduino question about hysteresis.