Try it; the body adapts, and you'll save money by not heating as much water. I've been cold-shower-only since December 2020 (not so bad in the Washington (state) summer, but in the winter it's a bit rough, as the water-delivery pipe is not far under the ground-surface). Inspired in part by the My Octopus Teacher guy who started swimming in the ocean off the southern coast of South Africa, and by an older man I remember visiting my classroom when I was in gradeschool, extolling the virtues of cold showers (general health benefits, if I recall correctly). It helps with my mental health, at least, practicing doing things I don't really want to do, and it feels wonderful to be done showering, rather than staying in the hot water because I don't want to face the cold bathroom.