I finished the 7 day Challenge today. I did four rounds in 1:15, 1:30, 1:45 min. My (final) hold was 2:25 long. I tried to trigger the diving reflex with a cold wet cloth. However, as it is super warm today my body was shocked by the cold which made my heart rate rise. Therefore, I tried again. This time I put the cloth on my chest while I did my preperation and pulled it over the face when I started holding my breath. I could feel my heart rate dropping instantly. My final result is 3:15 min. I will continue to train because I feel that I can reach 4 minutes just by resisting the twitching of the diaphragm longer.