If you enjoy running, but you don't have the endurance to keep up a fast pace for a long time, you can split those 30 minutes in two running sessions a day: 15 minutes in the morning and 15 minutes in the evening. The speed for each session depends on you only. There is no minimum or maximum speed, although, as reference, running one mile in 9-10 minutes is more than enough to keep you fit.
5. Interval Training
If you don't like jogging because it's too monotonous, try doing intervals on the treadmill. Intervals alternate high and low speeds and are wonderful for the body. You not only build speed, endurance and strengthen the main muscle groups, but you also do efficient cardio exercise.
Intervals are one of the preset workouts available on almost all treadmills. Choose one of the preset workouts from the console to train. The preset workouts automatically control the speed for each segment, and you get to choose from different levels of intensity.
Some useful piece of advice:
Before starting the daily exercise, always warm up for five minutes at walking pace. When ending the workout, cool down at a similar pace, until you can breathe normally again.
For relaxation, create some 30-minute playlists with your favorite engaging music, and play them while you work out.
Also, buy a pedometer to count the number of steps you make each day. Set the goal to do 10,000 steps a day, and program your workouts to reach this goal. Motivation is the key to all good things that happen to us in life, and this applies for exercising too.
If you don't have a treadmill yet, and you'll like some advice, read treadmill reviews via the site on my author's page. There are good options you can choose from for all budgets.