Choose a time period to take a shower for (like, 45 seconds), set an alarm, and instead of fighting through it, get in the shower, turn on the water, and helplessly give up, collapse under the cold water, and let yourself out when the alarm goes. You only have to do this once or twice to convince yourself you can physically survive the cold water; from there, resisting it should be easier.
Choose a time period to take a shower for (like, 45 seconds), set an alarm, and instead of fighting through it, get in the shower, turn on the water, and helplessly give up, collapse under the cold water, and let yourself out when the alarm goes. You only have to do this once or twice to convince yourself you can physically survive the cold water; from there, resisting it should be easier.
Note that this is a little bit extreme.
Thanks guys, epic explanation even with the casual extremity :)