I'm a mouth breather, lol. And my running coach told me to just breathe naturally. She said for beginners/shorter distances (we're not talking marathons here) that it's really not necessary to force yourself to breathe in a "pattern". When I was trying to do this (like breathe in for 3 steps, etc.) I never felt like I was getting enough air, either. Problem solved. (Of course it also gets better with increased cardiovascular fitness.)

You may be running too fast, and/or should look into some decongestants/non-drowsy meds for allergies. I have asthma but it only acts up now when it's really cold and I'm running/running really hard (for me)/allergies.

edited for spelling

Controlled Breathing
To me, this is more important then worrying about breathing through your nose vs your mouth when starting out. It took me 3 weeks of running before I learned this. The key for me was figuring out the sweet spot that was the fastest I could go, without slowing down. Consider the following...ignoring elevation like hills and stairs, and wear and tear on your feet and shoes, you can probably walk for a very very very long time or distance before being out of breath.. But sprinting, not so much. Somewhere between two extremes is your threshold of what you can take in as oxygen and process while moving. The capacity will increase some over time while your body also gets more efficient, but at the outset, your body can't easily do more then a walking pace without giving you that feeling of being out of breath in short order. In the first few weeks of C25K, I would recommend taking your speed, and slowing it down to a point where you know you're moving faster then walking, but just a little. Then, for breathing itself, try to match your breathing inhale and exhale with your pacing such that you're either doing a 2:2 or 3:2 ratio. The former is easier to learn, but the latter is more beneficial on improving efficiency and balancing the strain evenly due to the offsetting left and right strides.

Nose vs Mouth..
Until rather recently, I didn't put any preference to breathing in through my nose as opposed to my mouth. I find that if I breath through my nose I won't get as much oxygen, and thus can't push nearly as hard, but it does allow me to relax, keeps the sinuses clear and will heighten the senses.

Controlled Breathing
To me, this is more important then worrying about breathing through your nose vs your mouth when starting out. It took me 3 weeks of running before I learned this. The key for me was figuring out the sweet spot that was the fastest I could go, without slowing down. Consider the following...ignoring elevation like hills and stairs, and wear and tear on your feet and shoes, you can probably walk for a very very very long time or distance before being out of breath.. But sprinting, not so much. Somewhere between two extremes is your threshold of what you can take in as oxygen and process while moving. The capacity will increase some over time while your body also gets more efficient, but at the outset, your body can't easily do more then a walking pace without giving you that feeling of being out of breath in short order. In the first few weeks of C25K, I would recommend taking your speed, and slowing it down to a point where you know you're moving faster then walking, but just a little. Then, for breathing itself, try to match your breathing inhale and exhale with your pacing such that you're either doing a 2:2 or 3:2 ratio. The former is easier to learn, but the latter is more beneficial on improving efficiency and balancing the strain evenly due to the offsetting left and right strides.

Nose vs Mouth..
Until rather recently, I didn't put any preference to breathing in through my nose as opposed to my mouth. I find that if I breath through my nose I won't get as much oxygen, and thus can't push nearly as hard, but it does allow me to relax, keeps the sinuses clear and will heighten the senses.

Thank you for your advice. I can't breathe for anything when I run and it really holds me back. I'm restarting C25k again this week for the umpteenth time (never made it past week 3) and my heart and lungs always feel like they are going to explode long before my legs feel the slightest strain....and I'm only running for 60 blooming seconds! Hoping I can learn to slow down a bit and learn to breathe more effectively.

I *have* to do this: two short inhales through my nose and two short, almost forced exhales through my mouth. I get really bad pains on my side and get winded almost immediately if I run any other way.