A lot of people wants to run but find it hard to stay on running continuously for a long period of time.
Before everyting else you need to make a physical assessment including a cardiopulmonary exercise test. This assessment can be done in a clinic, gym, club or through your doctor. This will assess a patient’s exercise capacity.
The key here is practice, you need to make your body adapt to running and you need do it gradually you cannot do it in an instant.
Adaptation - in this step you'll gradually accustom your body to physical activity, your body will leave the state of inactivity to start an active state. The intensity of exercise is very light and its progression is not very pronounced. Patience and perseverance are very important at this stage.
Periodized Training - “Periodizing” your training is the key. Instead of doing the same routine month after month, you change your training program at regular intervals or “periods” to keep your body working harder, while still giving it adequate rest.
Alternate walking with running like for example in your first week you can walk for 4 minutes and run for 1 minute to complete the whole 30 minutes workout. Then in the second week increase the running to 2 minutes, gradually increase the running every week.
1st week: 4 min walk/1 min run alternately to complete 30 minutes.
2nd week: 4 min walk/2 min run
3rd week: 3 min walk/2 min run
4th week: 3 min walk/3 min run
5th week: 2 min walk/3 min run
6th week: 1 min walk/4 min run
7th week: 1 min walk/5 min run
8th week: 3 min walk/7 min run
9th week: 5 min walk/10 min run
10th week: 5 min walk/15 min run/5 min walk
11th week: 5 min walk/20 min run/5 min walk
12th week: 5 min walk/25 min run/5 min walk
13th week: 5 min walk/30 min run/5 min walk
Try twice or 3 times a week.