You're already sweating from a vigorous cardio exercise, so be careful when it comes to sweating some more. You have to stay hydrated. You can lose a lot of water during a workout followed by a hot sauna bath. You're going to lose salts and other minerals through sweating, too. Drink water before, during and after exercise, and make sure to drink some water before and after your sauna. If you don't like the “taste” of water, you can drink flavored waters or sports drinks if plain water doesn't tickle your taste buds. According to MayoClinic.com, you can lose up to 30 grams of fluids by sweating every minute or nearly 1 pint of water every 15 minutes. Don’t let dehydration ruin your sauna experience; be aware of the signs of dehydration, such as feeling dizzy, excessive thirst and a rapid heartbeat.