If you have kids, and they are a bit older, moving into the teens and beyond, have you ever had to justify why you couldn't do something because you couldn't afford it? Did the kids shower you with understanding and grace at being told "no?"
You most definitely aren't alone. Especially if you have had, in the past, been very willing to spend money to do fun things like have dinner out, go to movies, etc. From the kid's perspective though, they may think you are just being capricious, since they likely don't understand the realities yet of having to make hard decisions on what to afford.
I encourage you to break through that gap in knowledge and experience. You can do this by showing your budget to your children when they are old enough. Show them how much money is coming in. Point them too how much money is spent on food at home so they don't starve. Illuminate the costs that go into just having a place to live, the mortgage or rent and utilities.
They may react somewhat negatively at first. After all, this is the first time they are seeing that side of adulting and it may be hard to accept. Please try to be patient with them.
After a while, you may find that they come to accept reality as it is. So, please be open with your kids as appropriate with your budget. Let them see. By doing so, you are helping prepare them for life on their own.