This quote from Pastor Sebastian Kneipp describes one of the 5 pillars of the Kneipp philosophy: WATER.
Especially in the cooler months of the year, you can use Kneipp treatments to build up your defenses and naturally strengthen your immune system.
Stimulate your metabolism through temperature stimuli, e.g. through cold-warm alternating baths. Your blood circulation is stimulated, which improves the oxygen supply to your body.