If you're someone who usually cooks much more than they need by accident, then this hack is for you. It's sometimes a good idea to double up the amount of food you cook and then freeze it. It might cost a bit more upfront, but it'll save you money and time in the long run. You're basically cooking your lunch or dinner in advance, which means you won't have to spend more money on ingredients the next time you cook.
It'll also save you a ton of time since you won't even have to cook another meal whenever you decide to eat the saved portion of whatever you cooked.