"you negate the positives of a health lifestyle every time you make unhealthy decisions" is fundamentally incorrect.

I used to be a smoker. Each year I smoke one cigarette at an annual christmas party. One cigarette a year does not negate not smoking for the rest of the year. Likewise for food.

The main decision I have made is to be active. This is the best thing one can do for their health. I eat up to 100 grams of sugar per hour during intense bike races. I did a 160 mile race last year that took around 10 hours. Over the course of the race, I had around 800g of sugar (I burned around 7000 calories during the race as well) Despite doing this fairly regularly, I have excellent insulin sensitivity.