This is my current extreme heat and cold routine that I have been experimenting with and loving.

1) Wait until a hot part of the day.
2) Sit in car and use as a sauna w/windows rolled up. 15-20 minutes I sit in the back seat on towels (Breathing exercises)
3) Towel off the sweat and immediately jump into my chest freezer ice bath. Intro to my new Cold Plunge Deep freezer - YouTube
4) Cold therapy for up to 20 minutes. 32-40 degrees. (Meditation During)
5) Dry off and go for a walk. (Breathing Exercises)

Ironically, the hardest part of this routine comes a few minutes after the ice bath when sensation starts to return. It can be tempting to jump back into the heat, but I think the biggest benefit comes from forcing your body to heat itself back up naturally.

After doing this for a week, I can tell you that it puts cold showers to shame.

This is an accurate analogy- Cold Shower: Cold Tub :: Morning Walk : HIIT