Hi Nandini,
Its is extremely important to improve to running slowly. Distance running can be improved by looking ahead with our posture and practicing some stretching exercises before and after a run. To improve a run ,we need to look into our posture, like we need to keep our back straight , look forward keep your shoulders retracted to allow more air in lungs, This kind of posture will help to avoid straining your neck and back, and help covering more miles. Running is a cardio activity so taking up more of oxygen helps to give muscles to give a better performance. We need to also do some lower body stretching exercises like Quadriceps stretching, Hamstring stretching , IT band stretching, etc. We need to hold these each stretch for 20 counts. Also ,we need to progress slowly like brisk walking for some weeks then progressing to jogging and later running so as to improve better endurance.