I realize this is probably just because I am out of shape but I started the C25k today and WOW the burning in my lungs! I also felt weakness in my calf...Is this normal and will I be able to build past it?
Traumatic breathing is one of the first things you will encounter, and one of the first you will overcome. I thought I was going to die when I started training, even calling my Mom to say goodbye just in case. I was winning trophies a year later, lol. Of course you want to be cautious. A raw throat or irritated lungs, the taste of blood in the mouth - though not necessarily unusual - may make you more vulnerable to some airborne pathogens. Fortunately for you the weather is warming and the humidity will be easier on your lungs, though there is less oxygen in warmer air and less muscular blood flow to carry it (due to shunting of blood to the skin for cooling). Just take it easy and allow your body a chance to adapt. As long as you do not drive yourself to failure, your body will reward your courtesy with continual improvement, probably for at least another 10 years if you stick with it and don't run too far too soon, or too fast.