Exercising in hot conditions can lead to problems such as dehydration, fatigue, muscle cramping and even heat stroke. However, there are steps you can take which will help to prevent these problems. The most important one is to hydrate, water is fine for moderate activity but longer or more vigorous activity might require a sports drink. Pay attention to the UV index, humidity and temperature. Plan your workout route. Make sure to hydrate and eat post workout. Think about changing up your workouts.