Trick X Master
I went to a russian spa (banya) and did hot tub ->Sauna->cold plunge. The cold plunge really did it, it made my whole body tingle and my brain felt really clear for a few minutes. I did the round about 3-4 times, I spent 2 hours there. Cold plunge was 50-55 degrees, so pretty darn cold! I spent 3 minutes at a time in it.
So, yeah just really interesting, I'd say the endorphin feeling was more pronounced than any I have had since early 2007, indicating that my immune system has problem been messed up for a lot longer than I realized, more like closer to 5 years than the last 2 years that have been really bad.