The great thing about marathon is it’s not only a physical endurance test but also a test of your mental toughness. Less than 1 % of the people in the world are able to do well in marathon and finish it, so you are already a winner if you are able to finish the full marathon. The preparation can be broken down into two aspects that are diet and training.
When it comes to diet make sure you eat quality protein and a combination of raw vegetables and fruits. Do eat salads and grains which is very beneficial for training. If you are a vegetarian then you could use soya and whey as a replacement for animal protein. I would suggest increasing the ratio of the carbohydrate compared to that of protein and fats. Say, 70% of carbohydrate, 25% of protein and 5% of fat.
Ideal food runners to eat would be pasta that will take the number one spot. Pasta is a starchy carbohydrate which releases energy slowly and is low glycemic index is also beneficial for people with diabetes. Fish is an excellent source of lean protein especially salmon which is the king of fish. Eggs are another excellent source of protein which should be the staple source of protein for any athlete. Fruits like orange and apple can be added to the list. Broccoli, spinach, dark green cabbage, peppers and sweet potatoes can also fit in the long and important list of nutritional requirements of a distance runner.
Training is the something which people find most difficult to adhere too. Now it’s vital to condition one's mind to run distance as it’s the body that gives away first so if you train your body to listen to your mind rather than the mind listening to the body, then anything can be accomplished.
Running three to four times per week on an average is a good away to build endurance and avoid the injuries most common to first-time marathoners. Then progressively run up to 30 miles per week, I would suggest you to schedule you plan for 16 weeks so that by the 16th week you are ready and are equipped with stamina and the conditioning to finish a full marathon without a hindrance. As a final note planning and rest and recuperation is also critical.