How fast can the amount of time someone can hold their breath decrease?

Its plausible to pass 30 seconds, I can hold my breath for atleast pass 1 minute because of the amount of air I store and use in my lungs. I'm guessing if your friend smoked meaning he won't be able to hold pass 30 seconds because of the chemicals cussing his body to feel stuff and slower movement. Thats my opinion tho, I maybe be wrong. But I dove in Miami beach before, I held my breath for a minimum of 1:19. If that sounds impossible which is possible because the amount of time I practice holding my breath underwater increases the amount of air I can hold meaning my lung increases. Some people can't hold it pass 30 which is true, since they have less air to take in and out. I'm a swimmer