Mostly, it's my lungs that's getting tired out. My legs are completely fine for a while with some conditioning until I run longer than I used to. That's when I

Mostly, it's my lungs that's getting tired out. My legs are completely fine for a while with some conditioning until I run longer than I used to. That's when I experience pain, because my legs is getting too tired. These days, it's alway one of the other but never both. At the start, both my lungs and my legs are pretty much exhausted. Now my lungs and legs can endure for much longer.