Great Teenage girl workout and diet plan…?

I am seventeen years old and over weight. I have been overweight for most of my life and I am going into my senior year of high school in the fall…I have started walking 2 miles a day, back in April, but it only lasted for two weeks and then I stopped it. I want to be healthy and I want to be able to do things every teen can do. I was wondering if anyone can give me some tips on workout plans and on diets. I am lactose intolerant, so I can not eat any diary produces. Please, no harsh comments. I am just looking for some feedback and advise!

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