What do y’all eat?

I get exhausted throughout the day and I have a feeling it’s because I don’t eat the right things. To know about me, I’ve got IBS and lactose intolerance, so I’m picky about what I eat during a school day. Do y’all have tips for food that gives you energy? What do you pack for lunch and eat for breakfast? Any idea would help! Especially if they’re affordable (I’m a new-ish teacher so I’m broke af lol). Thanks!