I don't understand how is my mom not dead?

ok my mom has been smoking since she has been 17 she is now 50 and the doctors said her lungs are perfectly normal and fine like no damage same with her mouth this also happened to my aunt does this mean our family is amuned to smoking, also does she just not inhale into her lungs with here cigs if so is this possible and how do you do this also how is she not dead o and is that thing true where if you smoke 1 cig you loose 10 Min's of your life is is it saying you are wasting 10 Min's of your life