Unless you are very physically active and/or have a demanding job, you don't need to eat three times a day (bar medical requirements). I only eat breakfast and dinner, and maybe if I get hungry in between I'll eat a couple of crackers. Most people eat too much. Do remember to eat breakfast though, it's essential for keeping your blood sugar up during the day, even if it's just a light meal of cereal. Without breakfast you're likely to end up overeating later on.
If you're lucky enough to acquire fresh spinach or kale, the excess you can't eat straight away can be pureed in a blender, poured into an ice cube tray and frozen. The cubes last for months and months in the freezer. They are delicious in a smoothie with an old frozen banana and a bit of apple for sweetness. If you have a little spare cash, consider buying some matcha powder. It makes a green smoothie taste absolutely amazing.
Speaking of matcha, and of tea in general, if tea is something you really enjoy, visit a Chinese or Asian grocery store. They will usually have a wide range of teas for much cheaper than is in a supermarket, and the tea will be better quality than its cheap supermarket counterparts too. If you're prone to snacking, I recommend you invest in a good tea collection. Tea satisfies the tastebuds and engages the mouth, which is exactly what boredom snacking is about. It's also good to make up cold and keep in the fridge for ice tea, as an alternative to expensive juice or soft drink.
If you're absolutely desperate for a snack, buy popcorn. Not microwave popcorn, loose corn like this:
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See this? It's $3.30 at Woolies. That's a shitload of popcorn, and will keep you in crunchy goodness for ages. It's easy to pop on the stove and just needs a little oil in the saucepan. (You can also pop it in the microwave using a paper bag, but in my personal experience, it just makes the popcorn taste like paper bag.) It lasts forever in the pantry if you keep it in an airtight container.