When Katharine Hepburn was a child she would take an ice bath every morning and swim regularly in the Long Island Sound. The actress lived by the mantra “the bitterer the medicine, the better it was for you”. She lived to be 96 years old.

Hepburn attributed her health to the restorative power of cold water, and she’s not alone in this belief; Olympic athletes plunge their aching muscles into ice-baths after intense training sessions, Tim Ferriss is a proponent of cold showers, as is extreme athlete Wim Hof.

To reap the benefits of cold water’s power, you don’t need to jump into the sea or take an ice-bath. Simply turning the dial down in the shower will do the trick. Incidentally, I started taking cold showers three years ago, and haven’t had so much as a common cold since.

The link between cold water and optimum health is undeniable. When the shock sets in, our breathing deepens and our oxygen intake improves. As a result our blood flows faster and our heart rate increases, leaving us with a natural rush of energy. The cold water helps our arteries pump blood more efficiently which lowers blood pressure and boosts our immune system.

Cold showers have such a profound impact on our mental health that medical professionals recommend cold shower hydrotherapy in the treatment of depression and anxiety. When the brain is exposed to cold temperatures the adrenal hormone norepinephrine is released, which has been clinically proven to offer an instant mood boost.

Wim Hof – who holds the record for barefoot half-marathon on ice and snow – swears by the cold. Clinicians have tested his approach – which involves embracing the cold – and have found that as well as a slew of positive health benefits, cold therapy can relieve the symptoms of asthma, fibromyalgia, arthritis and COPD.

For a rebel entrepreneur, cold showers are transformative. They build resilience. The rebel entrepreneur knows that getting through the initial 20 seconds of cold makes any other issues in their life seem easier to handle.