How to stop my food craving/ eating when bored?

I have a problem whenever im done with my lunch, I always end up going to get a sweet after and think "hey its just a treat". I feel pathetic afterwards and I want to break the habit but I always just end up going to get it. I also have a stupid habit of eating when I get home from school, I know its okay for a snack but I always go bacj for more. The scale is starting to show im gaining and I feel like I instinctively just go for more snacks. Any advise? Thanks