for shortness of breath, anxiety, asthma, tachycardia, you might want to check out the powerlung device that competitive athletes use. There are some testimonials on the site for these conditions. With racing heart, you're not getting enough oxygen in the blood so your heart has to work faster.
"PowerLung is an easy to use, hand-held product proven by independent clinical studies to increase lung capacity and improve your breathing so you can race faster, dive deeper, perform longer, exercise easier, and, overall, breathe better.
PowerLung is right for you whether your goal is to improve your competition edge, expand your performance range and projection, get more enjoyment from practice, workouts or weekend athletics, or simply enjoy afternoons with the kids."
I just got one of these "the trainer" and after two days using it feel like I've been suffocating for years b/c I can breathe so much more deeply. For some of us it is very difficult to take a deep breath. The muscles can get really tight, weak, or the stomach can get sucked up into the diaphragm (a common problem). I'm so much more relaxed. It is a genius little device with lots of clinical research to back it up. Considering the oxygen/candida connection & longevity...we lose 40% of our lung capacity by age 50...lung capacity is the greatest marker of longevity. Great investment I say.