Thursday evening, and you want to end the week cold? OYA sets up in residence at Spark Club, the infrared-sauna studio in the Sentier. A collective 7km run through Paris at seven, then the contrast ritual: guided breathwork, a two-degree ice bath, and the sauna to thaw out. Bring running kit, a swimsuit, and a towel; changing rooms are on site. Forty euros. The breathwork and cold immersion carry real medical contraindications, so read those before you book.