If you take a cold shower every day you should notice the water “getting warmer” within a week. After a month of this it should be a solid habit and you’ll feel smug whenever someone talks about taking a hot shower after the gym or whatever.ere’s how to train yourself to take cold showers: 1  Turn the water on, set to cold. 2  Some people will tell you to start warm and decrease the temperature slowly each time you shower, then start a little colder each day.