For the seventh year in a row, Finland has been ranked as the happiest country in the world by the UN World Happiness Report. But we can all enjoy the benefits of the celebrated Finnish way of life. In their new book, The Power of Hot and Cold, authors Katja Pantzar and Carita Harju show how the Finnish tradition of hot and cold therapy is proven to dramatically boost our mental and physical health.

Canadian journalist, author and daily cold-water swimmer Katja moved to Finland 20 years ago,…