I feel better for next few hours after a cold shower (maybe for whole day? but im just starting), someone said they help with circulation and grow testosterone. is it true??

Also, how long and how cold? i usually go from hot water to cold step by step its not even hard haha. i had feeling today i could go for colder water but i was scared of heart attack lol or something.

do you guys go as cold as you can and how many minutes?

is heart attack or something bad possible?