Someone at the office pushing cakes and chocolate? Drop some extra apples and bananas at their desk. Soon they'll be pushing oranges and grapes at you!
Shop for groceries after a good workout, you're less likely to buy junk and more likely to buy healthy items.
When cooking healthy foods, cook enough for a few days. That way it becomes just as easy to grab something healthy as it does something not so healthy and you'll be more likely to choose the healthy stuff.
I won't keep sweet stuff around the house. If I am really craving chocolate, I'll make myself go to the gas station and buy two pieces of chocolate from the 25 cent bin. That's less than 100 calories and is enough to curb the cravings!