I can imagine the situation of you. I am imagining it because I never faced it. Your past lifestyle isn't allowing you to maintain a proper diet. Do feel demotivated. Nothing is going to change overnight. You maintained a diet for 6 days and I appreciate you for it. The first time 6 days is not so bad. next time keep to maintain it minimum of at least 10 days and little by little increase the gap. It might work for you. It's hard to directly change for you. So you can follow this strategy if you like.

I really wanted to start walking but haven't found myself doing it yet,

In that case, I am not supporting you. It's just an excuse nothing more. You are just delaying and you know it better that it's not good for your health.

Wishing you a healthy life.