Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to run a fast half mile [title] Build endurance. [step] Before you build speed, you need to build the endurance that will let you run the full half mile. Add sprinting into your regular running regimen to start building endurance.

Ending1: [substeps] Start with smaller distances, such as 100-meters, and work your way up. You might also start at 200 or 400 meters, depending on your experience. Ending2: This will help keep you off your feet for the entire half and keep you mentally level. [substeps] Practice sprinting for a week or two before a race or event that you want to race in. Ending3: You will want to aim to really jump up high to achieve these needs. [substeps] [substeps] Begin your run with a sprint that is at least 10 yards (60 m) in length. Ending4: [substeps] Think of your joggers as people. Imagine each individual step you take over and over again.

Answer format: ending1/ending2/ending3/ending4