Hello and welcome to DB
To practice holding your breath longer you should concetrate on the quality of the training and not the quantity. So set aside 15 to 30min a day some place quiet and comfortable like on the couch or the bed not while you are driving your car or cooking in the kitchen
Pre-breath holding breathing- Relaxed body, small breath in with the diaphram (low belly should move and not the chest) hold for one or two seconds then a long exhale, seven to ten seconds hold the exhale for one or two seconds and repeat. Adapt that breathing pattern to what is comfortable to you, the goal here is to lower the heart rate and to prepare you mind, after 3to5 min of that take one full inhalation, begining in the belly then to the chest, sholders and neck followd by one full exhalation. One to two normal breaths followed by your peak inhalation, same as above, and hold.
Start your watch but don't think about the time or look at it. At some points the hold will be painfull or stressfull but do your best to just keep the body relaxed. When you have had enough, you will exhale and probably spit all over the place

then breathe in and out short and quick 6 or 8 times to move the gas.
Do 3 sets and call it a day. If you keep a log you will be suprized how quickly your times will increase. Up to a certian point.
That's when it gets tough.
Don't do any of this in the water, unless you have someone expierenced watching you, and that does not count lifeguards!
Have fun
