Diets are hard. They are mostly so challenging because of the mental aspect, in that you are constantly telling yourself "No!"
And saying "no" to things you like all the time can be both physically and mentally draining.
So... stop saying No!!
Instead of focusing on all the foods you CAN'T have, instead start focusing on all the great food you CAN have.
For example, I love cookies. The more I think about the warm, chocolately gooey-ness, the more I want it. And then add on the fact that I am telling myself "no"… that only makes me want them more. It's only human nature that the more we aren't allowed to do something, have something, or see something… the more we want it! So instead of thinking about all the things you can't have, refocus on all the wonderful, delicious (and not to mention, probably 100x more nutritious) things you can have.
Like I have mentioned before, I love my morning oatmeal, I also love sweet potatoes, apples, green snap peas… there are so many wonderful things I CAN eat and LOVE to eat, that when I start focusing on those, my cravings for that cookie get less and less until they disappear.
So do yourself a favor, and STOP SAYING NO! Instead say YES to all the yummy healthy foods you can eat, and I promise that your cravings for junk will seem much more manageable.