One test that convinced me to stop smoking is the straw test. I worked with a community nurse who tried to make me realise how COPD breath and a daily basis. She gave me a straw of 1 mm diameter and she said: "Now breath in and out through the straw, pinching your nose, for 1 minute. That is how COPD patient breath and that is how you will end up if you carry on smoking!" It is said also, with the straw test, that if you don't feel uncomfortable with the test it maybe because you have a lung condition (i.e. asthma), but if you are not known as asthmatic, you should be worry about your lungs, because if you feel uncomfortable with the test, it does mean that your lungs are still healthy. Feel what a COPD patient feels with a straw test, it may convince you too to stop totally.