Looking for easy, filling meals for long volunteer days

I spend a lot of my days installing solar panels and then head straight to volunteer shifts, so I really need food that keeps me going without a lot of fuss. I’m trying to move away from just grabbing whatever’s convenient, because I usually crash halfway through. What do you all eat when you have back-to-back commitments? I’m curious about meals you can prep ahead that are actually satisfying and don’t weigh you down. Any favorites that combine good protein, some complex carbs, and maybe a healthy fat? Bonus points if it travels well in a container!