text: what could be causing a shortness of breath? sometimes i get short of breath for no reason.  when it happens, it's like i have to breath in a little bit deeper to feel like i'm getting enough air, but i don't have asthma because i don't wheeze.  i also tend to yawn more when it happens.  i don't get light-headed though, and it doesn't seem to be serious, but it's uncomfortable.  i'm just curious what causes it.  i haven't been able to find any patterns as to why it would occur.  does anyone have any ideas? (by the way, i am physically fit.  in fact i'm a runner, but  it doesn't seem to be related to any type of exercise i do.) the yawning suggests you're not getting rid of the co2 from your lungs very well, which also suggests that there's something strange going on.  do yourself a favor.  even though it's not bothering you much right now, go see a doctor about it.  it could be symptomatic of something serious that's brewing, and the sooner it's found the better.