Training for a marathon can be a difficult task for anyone, as it takes a lot of hardwork and commitment. Once you register for the marathon of your choosing I recommend you giving yourself 6–12 months of training. During your training process you do not want to overwork your body as you can put yourself at risk of injury. You should build up your running endurance slowly each month by running 10–20 miles a week until you feel you are ready to increase. It may even be a good idea to register for a small races, such as half marathons or even 10ks. This is a good way to have your body ready for the marathon.
Hydration is extremely important while you are training and it is especially during your run. I suggest you to drink a gallon of water a day since you will be training hard. You should bring a water bottle with you while you are running so you can stay hydrated. During the marathon there will be many stations that will supply water, which is great but if you would like to have water on you at all times I suggest you buy a hydration pack.
It is very important to get a good night sleep before your big day. You should also drink a lot of water the day before as well having a few glasses before you start running. Wake up extra early so you can enjoy a high-carbohydrate breakfast a few hours before the race. This is very important because you can fuel your body with the proper nutrients it needs to perform at a high level.
It is a long race, so my advice is to start slow because if you try and get ahead right out of the gate you may be struggling to finish. Remember is it a marathon not a sprint, so pace yourself at the beginning and you will be fine. If you are feeling fantastic during the run and want to pick up the pace then do so.