I generally hate leftovers (I’m pretty picky) but roast is one of the few things that I enjoy eating the next day. Then, the day after that, when the potatoes and carrots, the rice and the greens are gone, I get roast beef sandwiches. Mmm mmm good.
I tend to have certain things in the house at all times, like lunch meat and several cheeses. If you alternate the method and the bread, you can get a lot of good stuff out of it. One day, have a cold-cut sub. Then the next, pile up some pastrami or whatever on Texas toast and slap it on the griddle. Then maybe a regular sandwich with classic Mrs. Baird’s (or Wonder, depending on where you are) white bread.
The other thing I like about keeping a variety of lunch meat is that you can make a really good chef’s salad. Now that the weather is heating up, I like to make a sort of Italian style salad as a meal in the evening. Iceberg and Romaine lettuce, a couple of different varieties of lunch meat, torn up, green and black olives, couple of cheeses (usually one wet and one dry) and (for me personally) some of those little salad shrimp - I get mine cooked and ready to go in a bag for a very reasonable price.
The old standby of Ramen noodles can be dressed up - I make a pretty good caserole out of it, with cream of chicken, mushroom, whatever soup. I actually made myself a little Dorito’s caserole today (anytime I do this, I use those small disposable aluminum pans, sort of what you’d make a little bundt cake in.)
Depending on what level of coronary health you desire, you can always make individual Frito pies in the oven. If that’s a little much, a homemade chicken pot pie is easy, and since they sell ready-made pie crusts in the frozen section, you can just use what you need and re-freeze the rest. Can of chicken breast and a can of Veg-All, stuck in the oven till golden is VERY good.
If you want to broil a steak, get the 2 pack, and separate them before freezing. One goes to the freezer, one gets cooked. Nuke a potato until it’s done, then scrape out the meat. Add a little cheese, sour cream, and milk to the meat, stir it up really well, then place the mix back in the potato skin and stick it in the oven while your steak finishes and you’ve got a pretty quick and easy twice-baked potato. Add a slice of Texas toast and that’s a meal for one.
I also like to make a tomato and meat sauce, then divide it into single-servings and freeze them. When I want some good s’ketti, I just drop the sealed bag into the boiling pasta water to thaw it, and it’s ready to go when the pasta is.
Dunno if your tastes are similar to mine, but there’s my life.
ETA: to add to what was said above about pizzas - I get the canned biscuits and make little mini-pizzas out of them. You can scale up or down the volume to meet your needs on any particular night.