Learning to hold your breath for longer periods of time can be useful for swimmers and divers. Keep in mind it is a little harder to hold your breath under water due to increased pressure. There are techniques to learn that will help with this but you will have to practice to be able to increase your time.
Begin by holding your breath and timing it so you can see your progress. You can use a watch with a second hand or a stop watch. Write down your time in a notebook so you can be inspired by keeping track of your progress.
Learn to do breathing exercises. Breathe in through your nose as deeply as you can. Hold for a count of four then breathe out through your mouth. Do this for 30 seconds. Rest for 30 seconds and then do it again and breathe in and out harder this time.
Rest for a minute or two and then breathe in as deeply as you can and hold it. Don't hold the air in your cheeks. Remember to write down your time.
Do your breathing exercises once in the morning, once in the afternoon and once at night. It is not good for your lungs and general health to hold your breath repeatedly. Hold your breath after a few minutes of rest each time and time yourself. You should see improvement within a week.