I'm currently taking the SSI freediving class and I have a 2:30 static and am hoping to work up to 3 minutes for my next goal. There are apps for iphone that can help you practice and get used to O2 and CO2 build up called "tables." Take them slow and don't do them on the same day, but they should help! Before I started the freediving class my longest breath hold was 1:20, so I almost doubled it with just a little practice.