Karie, you can definitely do this.
Start with the diet. If you so feel like doing any moderate exercise, like walking, go for it. But don't plan it. When I first started reading the PB, I actually felt inspired to go for a walk, even though I was still concentrating on the diet part.
Good on you for starting today by cleaning house (pantry in this case). Make sure you get lots of veggies and fats, because when you find the right mixture, it's going to give you the most energy you've ever had.