Cold Water Exposure and Immune Function Study

The purpose of this clinical trial is to explore the effects of a 4 week cold-water immersion (CWI) intervention on measures of immune function, sleep quality, mental health and well-being, and muscular strength. The main questions it aims to answer are: * Does a 4 week CWI intervention improve measures of immune function, sleep quality, mental health and well-being, and muscular strength? * Are there any differences in these measures when comparing cold tubs versus cold showers? Researchers will compare chronic use of cold tubs to cold showers to see if cold water immersion may improve overall immune health and well-being. Participants will: * Undergo 4 weeks of Cold Tub or Cold Shower interventions at a frequency of 3 times a week for 4 minutes, if placed in the CWI intervention groups * Undergo testing measures at the two pre- and post- intervention time points, if placed in the healthy control group or the CWI intervention groups