Hi Cherry Blossom and welcome!
Good for you for making changes in your lifestyle!!

I agree with what Boop says and wanted to add to that....
1. Ditch the pop. In my pharmacy we have a saying: "It'll pickle your brain". Those ingredients just create an addictive cycle in your body and really can do damage when one is drinking as much pop as you do. Start increasing your water intake. I'd say for every glass of pop you have, you have to have the same size water and then 2 glasses of water to every glass of pop, then 3, etc. so you can ween yourself off. Water is essential for our bodies and it flushes fat and toxins from the body.
2. Ahh, those veggies. I eat a lot of veggies and maybe it's time to experiment with cooking! I also use Mrs. Dash products and use it on all my veggies. There are wonderful saute's and soups to try using Mrs. Dash. Maybe try a low-fat veggie lasagna with cottage cheese using squash, zucchini and mushrooms. I use Mrs. Dash Montreal Steak seasoning on mushrooms (portabella or other) with a bit of Ex. Virgin Olive oil and it's wonderful!! I use my South Beach Diet cookbook a lot. It has excellent recipes!! Try the Hearty Minestrone: it has little pasta and green beans, I believe. But you could add whatever you like with minestrone!
3. Gotta move! Just walking helps so much! Maybe try mini-goals each day like I'll go to this area and back and then the next day, go a bit further (to the big pine tree) and back until you can build up to your big goals. If you have a place where you'd feel safe and comfortable, maybe do a bit of swimming to help take some pressure off your knees. I go to the Senior Center occasionally--there's no judgment there!
4. Keep a journal. Record your food, exercise and feelings. Then you can look back and see what your triggers are. Just try and remember not to be too hard on yourself if you have a bad day and fall off the wagon. Just hop back on the next day. We're human and this happens!
I applaud your efforts! You can do this. We're all cheering for you! You are important and your health is important!