Hi,Manoj the way you are doing is correct as by doing this adaptation to particular speed is prevented.But take care when you start, do with slow speed and gradually increase and then again slow down your speed as you finish your exercise session. With this you will do both warm-up and cool down. Also have a check on your heart rate, it should not fluctuates.Your heart rate should rise gradually and come down as you finish.
Remember if you have any discomfort stop doing that exercise.If you have any more queries feel free to ask.Enjoy your workout, live healthy.