This short Ted Ed video gives a great, animated explanation of how sugar affects our brain and why it is so hard to give it up. The good news–when you start limiting sugary foods for just special treats it becomes easier to eat less of it and your cravings for it become more manageable.
The video also explains why variety in your daily meals is important to help keep the reward center of our brain satisfied and active. You are unlikely to be successful with healthy eating if you eat grilled chicken breast and salad too often.