If you've gotten rid of the junk food and you've learned the basics of meal prepping, in my opinion, you've already completed the hardest step.
You hear it all the time - "80% diet, 20% exercise". Personally, I believe it's more like 50/50. I say 50/50 because you need both exercise and good, healthy food options. You can't reach your goals without each of them.
Another reason I say 50/50 is because life is all about balance. You shouldn't live your life on a crazy diet "fad" nor should you dive into a fast food cheeseburger any chance you get! Do not restrict yourself. That's how "dieting" fails. Do not call it a "diet". It's a lifestyle. You can make small, healthy swaps and you can also enjoy your favorite dessert. Do not binge, it brings out your cravings! Allowing yourself to enjoy treats here and there allows you to adapt to a healthy lifestyle while also treating yourself. Because let's be honest, if you are diving into fitness and reaching your goals, you deserve it!
We all make mistakes, big and small - we're human. I struggle with it sometimes, as well. A big thing that helps me stay committed is thinking about when I finish a workout. I feel amazing! The last thing I want to do is ruin the progress or that hour of hard work on a burger and fries. Instead I fuel my body with what it needs - a good carb, protein, and fat.
Don't get me wrong, sometimes after a hard workout, I want a cheat meal. And in other cases, I remember why I started. Exercise is beyond amazing for you, but exercise and results do not come unless you fuel your body properly.
Keep trying! You're never going to be perfect, but it's about your effort.