With a 10Lt 232bar cylinder it’s easy to last an hour, even in 7’C water. Nothing special, just dive more.I had a standard tank and was not under any sort of overexertion. Depth was between 60 and 30 ft. This was with a guided dive with a DM. A lot of people were giving me **** saying that if you had bigger lungs that meant you were taking in more breaths but that's not how this works. With this guy's breathing program you take almost half as many breaths while your lungs are increased by about 20% which gives you a net reduction in consumption.