Getting cold triggers body stress responses that are good for you. Cold plunges are good for this, but not very accessible. Cold showers are readily available to most of us, and this article tells you how to build a habit of taking cold showers.
I also do sauna for similar stress response benefits. I used to balance sauna with cold afterwards (either plunge or shower) but recently I learned that the cold afterwards stops some of the benefits of the sauna stress.
So I’m flipping this, and doing sauna and cold on opposite parts of the day. If I do sauna in the morning, I do a cold shower that night, and vice versa.