Hi, I was hoping to get some advice to improve my freediving. Sitting still I can hold my breath for 4:30 minutes on land. While I am diving though I feel like I cant get calm enough, or I burn to much oxygen to stay down long. When I fish I can usually only comfortably stay at 15 feet for a little more than a minute. The deepest I have dove was 85 feet. Are these reasonable numbers for a 4:30 static. I sort of feel like I should be able to stay down longer. Thanks for any help or "tricks of the trade" that you can give me!