This might work. It's one I've posted before.
Do a 30 minute session and split it into 10 3 minute "cycles".
Each cycle works like this.
You walk for 2 minutes 50 seconds and jog for 10 seconds.
Do this 5 times a week for the first week. I would suggest not doing the 5 days straight, do it perhaps 3 on, one off, 2 on, one off, so you're not doing 5 days, then doing 2 of nothing back to back.
In the second week change each cycle to this.
You walk for 2 minutes 40 seconds and jog for 20 seconds.
In week 3 you change each cycle for this.
You walk for 2 minutes 30 seconds and jog for 30 seconds.
Eventually you should be able to go for 30 minutes of continuous jogging.
Use a pretty flat course to start with, until you're able to do a whole week of complete jogging, then you could change things in one of three ways.
1. Use a tougher course, eventually going for a longer route.
2. Jog for another 5 minutes per session increasing your total jogging time week by week.
3. Try to go for more distance in 30 minutes, by speeding up.
Perhaps this might be of help to you

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