The most common mistake when trying to eat better is trying to change everything at once. Drastic diets fail precisely because they demand too much willpower from day one.
One small, sustainable change — like keeping fruit in sight in the kitchen instead of biscuits — has more impact in the long run than a strict diet you give up after a fortnight. Start with a single change. When it becomes automatic, add the next one.
Start today: just one change. The afternoon snack. Everything else stays as it is.