I did 3m06s in a pool, very much like those apnea competitions. I had a spotter and people around me in case something went wrong.

For me the idea of controlling my body and mind to do such a feat felt like a huge accomplishment. It requires fighting off reflexes, relaxing my muscles and reducing my thoughts to the bare minimum so as to use the least oxygen possible.

Control and determination are tested and it feels great to overcome these things.

I stopped practicing apnea because I didn't have any data on how it could affect my brain negatively but I still am very proud of my accomplishment. Also before I started I couldn't swim a full lap underwater without coming up for air but now I can do it without any problem.