sit down at a table with a regular drinking straw and a clock that has a second hand or digital clock that counts seconds.
Now...the only air you may breathe must come through that straw for the next 3 minutes. time yourself
You can't seem to get enough air through the straw can you? It's panic time isn't it?
Yet, you rarely even think about what smoking is doing to your lungs.
Start thinking about it.
This is how smokers end up, with diminished air capacity struggling to breathe.