Training for a 5k

I started Weight Watchers Online for Nursing Moms about 6 weeks ago. I have been walking with the boys a few times a week, but no serious exercising. Yesterday, I started training for a 5k (3.1 miles). The program I am doing is a 6 week program of run/walk cycles that gradually go from mostly walking to mostly running. By the end of the 6 weeks, I should be able to run a 5k without any walking. The program has me running Monday, Wednesday, Friday, and Saturday. I am also trying to do so arm and ab work on Tuesday and Thursday. Sunday will be my day off. I am hoping that by toning up my arms and legs and strengthening my core, the weight will start to come off more easily.