Cool no problem sorry to derail your thread although you need to loosen up man. You aren't even still talking about what the initial question was in here, which was will these supps help me. Not likely at your age. I also would not train with anything that is going to help you increase your stamina or endurance like cordyceps or creatine these vices wont be available during your seal training. Suddenly not having them helping out will actually diminish your performance. Would be kind of like running jet fuel while getting ready for a race then running regular unleaded during the actual race. Not a good idea. You want your body to run optimally with less, not more leading up to that training. I would avoid all performance enhancing supplements since you won't have any during Seal training.
You really need to practice drowning. Not being a d*ck either, you need to practice drowning if you want to be a seal. I have heard over and over that is the part that people quit at man. The under water defense and what not they steel you air, cut your hoses, attack you and do whatever they can to make you panic under water if you drown and pass out you get revived now get back in. SO you will want to find a way to simulate some of that and get over the panic. Perhaps get under water and hold your breathe, then have a buddy wait 20-30 seconds and then have them hold you down and make you fight to get back up for air. Have a safety signal of some sort that you can do so he knows when to actually let you up. Get yourself used to that stuff from what I understand once you master the fear and panic the controlling of your system becomes much easier. I would also start practicing swimming in natural bodies of water with currents and what not like the ocean, rivers or lakes it is way different than swimming in a pool.