When i run, my lungs get tired before my legs do.i have trouble catching my breath but could keep running. what would cause this/ how can i fix it?

Many causes: There are many potential causes. It is possibly hyperventilation (anxiety related), deconditioning (meaning you conditioning level is not good), vocal cord dysfunction, reactive airways. The best way to figure it out is have a treadmill test with cardiorespiratory monitoring, spirometry and possibly albuterol administration to see if it improves pulmonary testing