An added benefit is that you will probably become very holy the moment the cold water hits your body, because it is very likely you will shout, "Oh my God!" You might try exclaiming, "Wahe Guru" ("Wow, God is Great!") or "Ang Sang Wahe Guru" ("God lives in every limb of my being"). Remembering God is always a blessing.
Go in and out of the water four times, constantly massaging your body until the water no longer feels cold. Be sure to get the armpits (major nerve centers) and the insides of the thighs. You can even stand on one foot and massage the top of it with the other foot, but don't slip or trip. Women, be sure to massage your breasts.
Then, your first victory of the day achieved, dry off briskly with a rough towel till the body really shines; put on loose, comfortable exercise clothing, and you're ready to do your sadhana, your personal daily spiritual practice.