Hi Will, totally understand. It's incredibly difficult to motivate yourself and find positives when there are certain aspects of your health that are difficult to change (ie processed foods, few other people to help motivate and do activities with).
What it is important to do is to focus on the things you can change. I know, I know, easier said than done. But let me show you how.
First of all, we need to figure out what actions you can actually take. Saying you can't change anything is just an excuse, a barrier to you losing weight. We need to break down this barrier.
Here's a couple of things you can change (and there will be plenty more, this is just what I can see from your post):
Firstly it might be a good idea to find some fitness videos online that you can work out along to. It doesn't really matter what routine it is at this stage as long as it gets you moving and keeps you motivated.
In terms of the processed foods, whilst you may not be able to change what you eat, you can change how much. I'm not talking about calorie counting, that sucks, but just cut back a bit on the quantities. That coupled with an exercise routine and you should start to see the effects.
Now that's actually the easy part. Keeping up the motivation and trying to focus on the things you can change versus what you can't is hard. It will be tough. But you can develop processes for your mind to follow to get yourself back on track and keep in high spirits. It's probably worth just taking a little bit of time upfront and listing out your motivations for losing weight.
I usually ask myself the 3 whys. So, Why do I want to lose weight? and I respond "Because I don't want to be fat". Why? "Because I want to look good". Why? "Because I want to be attractive."
That there is my key motivation. If you do the same for your own motivations then when we're faced with barriers to losing weight, such as not knowing what we can change, just go back to your motivations, remind yourself why you want to lose weight and focus on that positive. This is actually a stronger feeling that any negative so will give you the motivation to taking steps to breaking down this barrier.
You've already done this here. You've found a barrier to your weight loss and you've come onto the forums to ask for advice. That's the first step. The next step, the hardest, is making the decision to act and make some changes. The last step is keeping it up, the next hardest part.
So, find out about your true motivations. Once you've done this you are better prepared to making necessary changes. Then actually make a couple of changes (see examples above, better still come up with more!).
Let me know how you get on!