I like to try for two blocks running and two blocks walking in between, with a goal of eventually running the whole thing some day. Just remember that when you add running, you will need to add some distance so that you are still out for about 30 minutes. Look in the mirror every day and find something positive in that reflection. It will get easier every day that you work towards your goal. During your work out, don't lose sight of your goals.
Some days go better than others.
If you have a low energy day, work out as much as you can and try to make up for it the next day. I have dropped from 198 to about 180 in six months. I haven't really checked the scale as much as I have the mirror. I dropped two inches from my waistline and I am working towards the next two, which seems a little more difficult. A positive attitude is key.