The challenge for day 22 may sound a little odd, but there is research to suggest a cold shower can be beneficial for your mental health.
We understand that it is the middle of winter, but that quick shock in the morning could be the key to getting you ready for the day ahead.
According to a study published on the National Library of Medicine, a cold shower could be a potential treatment for depression.
"Exposure to cold is known to activate the sympathetic nervous system and increase the blood level of beta-endorphin and noradrenaline and to increase synaptic release of noradrenaline in the brain," the study says.
"Additionally, due to the high density of cold receptors in the skin, a cold shower is expected to send an overwhelming amount of electrical impulses from peripheral nerve endings to the brain, which could result in an anti-depressive effect."
Move Strong Physical Therapy also says on its website a cold shower is an effective way to relax the body, with Dr Jared Packer offering three methods people can try.
1. Start slow
Dr Packer wrote on the website people should make the process tolerable. He suggests starting with a warm two-minute shower to increase circulation before decreasing it to a temperature that is noticeably colder.
He adds people should only feel mildly uncomfortable and notice their breathing rate increase.
"Allow yourself to adjust to the new temperature. Let your breathing return to normal," he wrote.
"Continue to incrementally decrease the temperature and give yourself the time to adjust to each new level."
2. In and out
Starting again with a warm two-minute shower, this method involves people backing away and decreasing the temperature.
In this method, you then move one hand in and out of the shower stream before switching over to the other.
"Gradually move up to your forearm, then to your shoulder," he said.
"Put your leg in and out, other leg. Then arm to neck and back out, and so on and so fourth.
"When you are ready, let the stream hit your head and neck, and eventually stay there."
3. Jump in the deep end
Dr Packer wrote this method involved just jumping under the cold shower and staying there until breathing returned to normal.
"Sometimes I will do this if I am very stressed out," he said.
"The shock can break you out of whatever is troubling you. There is nothing to think about but, 'wow this is cold'."
WARNING – Dr Packer does not recommend this method for cold therapy beginners or somebody with a history of panic attacks or other stress-related disorders that are prone to flare-ups, such as fibromyalgia.
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