Muscles need energy in order to function and contract properly and therefore need food supplies of glucose and oxygen. Endurance is a measure of the body’s ability to use energy efficiently and keep going longer.
Along with your aerobic training for the upcoming run, you can improve endurance through a carbohydrate rich diet - good sources include potatoes, bread, pasta and rice. Basic sports nutrition will include a diet based on around 60-70% of calories from carbohydrate to keep glycogen stores full. Maximize this a two days before the event “carb loading” to keep you going that little bit longer (through higher than normal muscle glycogen stores.
Protein foods such as fish, poultry, eggs, lean meat and beans will aid muscle recovery and keep a positive nitrogen balance. Water is vitally important to stay hydrated and isotonic drinks are also very popular.
Lessening you training in the final days before the event should set you up to give your best!