In order to build endurance to complete a half marathon comfortably you need to work on your aerobic fitness, mental stamina and physical fitness.
Half Marathon Endurance Tip 1 : Mileage
The way to go about those three is doing enough mileage. Ask any fast marathoner how much they run and you are sure to get something like, upward of 120 km a week. If 120 km sounds too much, start small, aim at 20 km then 30, 40, 50 km like that.
Half Marathon Endurance Tip 2 : Long Run
Once per week you should run a long run. The distance should be anything from 15 km to 20 km. The long run is done at slow steady pace, just go out thee and have fun at your own pace. The long is critical to your half marathon performance as it provides you with the aerobic fitness.
Half Marathon Endurance Tip 3 : Speed Work
Speed work is about trying to push your body beyond its limits. It helps in improving running efficiency. Ideally these sessions should be done on a track or flat grass oval. It about running at a fast pace.
Half Marathon Endurance Tip 4 : Diet
Remember to fuel your body. Eat healthy foods and make sure you eat enough. Have a small meal before going out for a run.
Half Marathon Endurance Tip 5 : Water
Stay hydrated. Lack of water is one of the main cause of fatigue
Half Marathon Endurance Tip 6 : Rest
Rest is very important in any training program. Rest allows your body to recover from fatigue and minor injuries. The body regenerates during rest. It is also important to reduce your training days before a race.