practice n try 2 keep sum air n ur lungs n let out slowly. relaxation

Chanel,
Your lungs can be trained to hold air longer just like your muscles can get stronger- through increasing loads. Using a spotter (someone to watch over you in case you black out), in the shallow end of the pool submerge your head for as long as you can while being timed. Twice a day hold your breath for the same amount of time (no pool necessary). Do this for 2-3 weeks, then retest under water. You should see an increase in time. Keep repeating this technique until you reach your goal.

Chanel, one thing you need to do to hold breath longer is to make sure you get as much carbon dioxide out of your system as you possibly can. When holding your breath, the need to take another is as much from co2 buildup as from needing oxygen. So try this. Before you hold your breath, take a deep breath in, a deep exhale, another deep breath in then exhale as much as possible, get the lungs as empty as possible. Then breathe in and hold it. Use this technique while following the practice schedule Jack suggested above.

A side note, DON"T hold your breath while swimming. Learn to exhale constantly while taking your strokes. Then take a breath stroke and repeat. I know it seems like you can be faster if you don't take the time to breath but it will actually be slower than learning to exhale and take breath strokes. Holding your breath can tense your muscles and they won't work as efficiently.

Lung busters. You swim as long as YOU can go swim underwater and come up for a breath when your lungs burn. The most effective stroke to do is either freestyle kick or body dolpin. I had the same problem. I was a good freestyler but I couldnt seem to be able to hardly make a 200m in a meet without almost dying. Lung busters are one of the most effective activities to strengthen your lungs so you can hold your breath longer. Dont push it too hard though. Swim underwater as long as you think you should go. If you dont push it hard, you wont improve, if you push it too hard, you can hurt yourself or pass out. Finding that balance between those two is hard but it helps alot.

swim it takes ur mind off of holding ur breath

for some reason i think goggles help