Learning how to hold your breath longer requires consistent practice combined with physical exertion. Begin by holding your breath while walking, and try to walk farther each time. After a week, practice holding your breath while swimming.
Practice breathing before every exercise session to ensure that you are inhaling and exhaling as much air as possible. Breathe in while slowly counting to five, then out for the same count. Continue this for several minutes. After this warm up, hold your breath and walk as far as possible before exhaling. The walk should be high intensity, fully engaging both the arms and legs. Do this three times, warming up before each one.
Use the same warm up before attempting to hold your breath while swimming. Stay underwater as long as possible while swimming laps. Note the distance you traveled, and try to improve it each session. Make sure to exercise in a safe environment and don't overexert yourself, as holding your breath for too long can cause a blackout.
Staying relaxed is an important factor in holding your breath. Practice keeping your heart rate down while holding your breath, so that unnecessary oxygen is not being consumed. Focus on calming thoughts while training to reduce stress. Additional cardiovascular training is also helpful for this because it makes the heart more efficient.