i got hit by a car and from not breathing correctly i get pins and needles through out my body and headaches, which i believe is because of muscle tension or something the doc said... i noticed that with constantly breathing in through the nose and either out through the mouth or nose steadily that i can relax and stop the symptoms of having an injured back. doing this to stay relaxed has in turn got me steadily very high frequently getting into intense periods of meditation that i was never really capable of before. it maybe because i abused psychedelics a great deal since injuring myself, but i did use a lot before and never really felt and experienced what i do now. sometimes my breathing gets me very high like being relaxed and euphoric high on opiates and sometimes feeling of like i'm rolling on E but not as stimulating. if i relax long enough i'm able to achieve psychedelic states.
with wim hoff breathing, i think that's too fast to get going and then when you do the 15 second breath hold, i would say that's too long and creates tension ime.. i read the book "The science of breath" and they recommend getting into 5 second holds for the breath, and most of the time that's even too long. if i did wim hoff breathing, like you mentioned you feel tense, i would feel really shitty nerve damage symptoms in my body and get a headache. nothing enjoyable about it. i find breathing in through the nose and out through the nose at a slow but relaxed and not pushing trying to be slow pace, just be natural breathing and try to ride that. kind of just relax until you notice your breathes start to get longer, and then maybe i can hold a 5 count breath in...
speaking of holding long breathes, when i first started smokiing weed, i'd have perfect slow long breathes through my nose, and i'd hold them for like 20-30 seconds and just lay around on the floor tripping out, but when i got hit by a car holding those breathes (life wim hoff would for me) caused pretty bad headaches and itchy pins and needles through out my body. i had to develop the perfect in and out breathing to help my nerves and muscles from being damaged. i held my breath in way too long getting stoned. it felt good though.
OP mentions they feel tense, when trying to achieve psychedelic states through breathing, it's best to be working on relaxing the muscles.. idk, maybe people get off on different stuff though and my psychedelic effect is just a psychological effect of relaxing. idk.