Fran, keep walking. I started walking 2 years ago (got myself Garmin vivofit). Today I am doing almost 15000 steps daily. It is about 7 miles.
Half year ago I got treadmill and start my first C25K. I lost about 16lb without diets, just smaller portions (my weight went under 200). I can run 5k now. I am doing my second C25K (faster time is a goal). And I started going to gym, and believe me, I am not a gym person.
All this started with silly pedometer....
Keep it up!