Soups are the best fall back. Veggies can be pureed with or added straight to stock. Choose a low sodium stock. Saute onions & garlic in a little olive oil or canola oil & then add your leftover veggies (& or meat) add stock & reduce. Add water to thin. Season to taste.
Toss extra veggies, chicken or steak on a salad the next day for lunch or make into wraps or sandwiches. All you need in the tortillas & condiments.
Leftover meat can be added to lasagnas or pasta sauces.
Veggies & meat can be put on pizzas. You can buy premade pizza dough & sauce or use marinara from a jar.
Have you drank all your water today? gotten in all your exercise? It's not too late!