I'm a beginner trumpet player. And I've noticed when I start to play it sounds fine but after 5 seconds of playing I start to feel out of breath, a tad lightheaded, and the notes begin to sound like a sheep is dying. Then when I stop playing I am out out of breath. I'm sure it's a problem with my air flow. I read on how to use 'circular breathing' but I don't think a beginner would need to use that. Also how you should get 'warm air' from the bottom of your lungs. I read on Wikipedia and other sources about how you can put a hand on your stomach and chest and the stomach should rise first. That doesn't seem to be working for me. Any help for a beginner?
tl;dr I'm out of breath after I play trumpet, what breathing technique will help this situation?