increase my cold tolerance

A few times I tried switching to just cold water after a warm shower. That just makes my body go crazy, and I can’t stand that very long! So now I’ve switched to increasing my cold tolerance gradually. I’m ending my showers with cool water for about one minute. Cool enough for me to feel the cold, but not so cold that I lose control of my breathing.

I tried finishing my shower with cold water for 10 seconds a few times. It felt great after! My whole body was feeling alive, and on a high. I’ll start doing some more of this each day now. :)

I swam in the Alps lakes last summer the water was between 4°C to 14°C (39 °F to 57°F ).
I want to do the same this summer.
I must go faster in the water and feeling better.
The goal is to go in the water in 1 seconds without being breathless or panic and have a good feeling of my body

I think that I have a pretty good tolerence to cold but I want to increase it.
And I add also cold shower interval training