"Free divers condition their bodies to tolerate high levels of CO2 using timed breath-hold exercises called static tables. Essentially, it’s interval training. Breathe two minutes, take four huge breaths, hold breath for two minutes; breathe one and a half minutes, take four huge breaths, hold for two and a half minutes, and so on. The aim of static tables is to increase breath-holding time while decreasing the rest interval. Within a few weeks, I hit my goal of three-minute breath-holds with only one-minute rests in between." - James Nestor