To prepare for physical activity in hot weather, drink 400–600 ml of water gradually over two hours before exercising. Avoid consuming all the water at once, as this can lead to discomfort. If exercising for longer than an hour, eat a carbohydrate-rich meal 2–3 hours beforehand, such as muesli or oats with berries. For shorter preparation times, opt for lighter snacks like a banana or toast with honey.