Walking and running will get you out of your breath easily.having a healthy respiratory system is very important.without it it would get difficult to get through our day normally.if the respiratory system do not function properly it would lead to death.some aliments cause respiratory disorders or pulmonary diseases.Like bronchogenic carcinoma(lung cancer),asthama,pneumonia,pleurisy,acute mountain sickness etc....                                                                                                                            inspiration also called as inhalation the intake of air.Expiration also called as exhalation is the process of pushing the air taken in. hope u have understood my answer. :)