Be Mindful of the Season
Like it or not, Ramadan is during summer now, and so be mindful of the heat and humidity. If you are tired during the day, do not hesitate to take a nap and rest. After sunset, make sure you drink plenty of fluids and stay well hydrated during the night. Try to avoid very salty foods so as to not be excessively thirsty during the next day. As a doctor, I would recommend avoiding any strenuous physical activity while fasting, if at all possible. And again, most importantly, if fasting causes you to become ill, do not continue, and seek medical help immediately. Islamic law has outlined alternatives to fasting for those who cannot fast due to medical or other reasons.