Don't beat yourself up for having that delicious chocolate cake.  You need to indulge every once in a while in the foods you love that are not necessarily healthy for you.  Just eat healthy most of the time with a variety of healthy natural foods.  Stay away from processed foods.  80/20.  If you eat healthy 80% of the time and give yourself 20% of the time for indulging....you are one step ahead of many.  Just don't make 20% of the time a habit that becomes 80%.
Here's to your health.
What foods do you like to indulge in that might not be health?