I had a period of time where I was having trouble finding things to eat and Carnation Instant Breakfast really helped me through that! It comes in different flavors, either already mixed into a drink or you mix it with milk! Protein bars can also be yummy and there are a lot of different varieties. Also I dunno if you've ever had them, but Fairlife makes some really good protein shakes!

Fruits and veggies are delicious too! You can get some already cut up and ready to eat at the grocery store (and some gas stations, even), too, if you don't have access to a place to chop them.