I am probably wrong but id say all of the above
I just make sure I drink water every 10 minutes or so and make it a game lol
CO is produced whenever a material burns. Homes with fuel-burning appliances or attached garages are more likely to have CO problems Common sources of CO in our homes include fuel-burning appliances and devices such as: Clothes dryers. Water heaters, cars, gas stoves, generators, and power tools
D in the morning, during this time you have been inactive for the past (hopefully) 8-9 hours or else you will be sleep deprived and your body is not at its 100%. Sleep deprivation could cause many disadvantages to your morning exercise and the day ahead. The most important is to start well rested and get at it with good stretching exercises and you will give your best to a better you. The hardest part about exercising in the morning is the mental battle that you will face with your "lazy self". The "lazy self" will keep pushing you to sleep more or eat that wonderful slice of cake from breakfast but you need to be able to battle this mental state and push towards a better you that only thinks of a healthier state.