If you can make dinners that also make good leftovers, you can kill two birds with one stone. One silly thing that changed how I felt about leftovers (they used to be something I knew I should take for lunch, but really didn't want to) was getting some really nice glass containers to store them in (we got glasslock ones, but there are others) - first, I can see what's in them in the fridge so I don't forget about stuff, and second, it just feels a lot nicer to heat and eat my leftovers in glass than in old plastic takeout containers, which is what I was using before. We spent a silly amount of $ on the glasslock (like over $100), but now I eat leftovers for lunch most days and actually enjoy them. If you portion out your leftovers into containers as you clean up from dinner, then there's no "lunch packing" time in the morning - you just grab your containers and go.
One favorite that makes a quick, delicious and healthy dinner plus lunch is taco bowls. I make some brown rice (Minute rice works fine for this and is quick), and saute up some onions and peppers (can use fresh or frozen), drain and rinse a can of black beans and throw that in, and add frozen corn and/or frozen broccoli depending on what I feel like. Top with shredded cheese (I buy the bagged shredded stuff to make these easier), sour cream, and chopped fresh cilantro, fresh tomatoes and/or avocado. No one of those ingredients is essential, so it's a really flexible meal. Sometimes I do cooked sweet potato cubes, leftover meat, or shrimp. With the leftovers, I put all the "warm" ingredients in one large container, with the cheese, and all the "cold" ingredients (any fresh veg & sour cream) in another container. At work, zap the warm container in the microwave and dump the cold ingredients on top. It's a meal I really look forward to all morning, and would cost $9-$10 at the lunch place down the street.