To maintain your jogging speed you will need to build your stamina and endurance, and keep a close watch at your speed and heart rate. Put simply, you can up your speed and maintain the increase by slowly working up to it by jogging everyday. Combine this with keeping track of your average speed and number of steps per session for motivation and so you know for sure just how fast you are going.
If you are new to exercise or running, you will probably not be able to maintain a set jogging speed for very long. Start by walking and then slowly break into a jog. When you get tired, go back to walking to catch your breath and then start jogging again as soon as you are recovered. Continue doing this is intervals until you can jog for the entire distance, no matter how slow of a jog.
As your stamina increases, you will be able to increase your jogging speed in much the same way. Increase your speed and then slow back down when you become winded, but this time do not slow to a walk. Instead, continue jogging at a slower speed and then increase again. Do this each day until you can finally maintain the faster jogging speed the whole way.
You may slowly add more distance to your jogging routines, which may require you to gradually add speed to each trip since you may want to start off a longer trip going slower than usual in the beginning. You may find that the more your cardiovascular health improves and the more you grow accustomed to jogging each day, the easier it will become to increase and maintain a constant jogging speed.
It is also a good idea to to check your heart rate and speed as you go along. You can check your heart rate manually by counting the number of beats in 30 seconds and then multiplying by two for your beats per minute. Compare this to your target heart rate so that you stay within a safe range. To accurately gauge your actual speed, you can purchase a pedometer that clips to your pants which will measure your speed and the number of steps you take. Some pedometers also measure heart rate.
Make sure you do not overextend yourself. Although you may have a goal to maintain a constant jogging speed for a set distance, if you begin feeling dizzy, faint, or overly exhausted, you should slow down or stop for a rest. During cardiovascular exercise, you should be able to talk in short sentences and your heartbeat should be increased but not uncomfortable. Be sure to take water along for your jog, and drink something at least every 20 minutes, or more often in very hot climates. If you experience an irregularly fast heart rate or chest pain, stop exercising and seek medical attention.