My bank balance lies- how do I actually know what I can safely spend?

I find myself consistently feeling like I can afford more than I can.

The root of this is basing my spending off of how much money I have in my bank account.

I’m great at creating savings goals & building plans, but when the end of the month comes, I’m always short in my savings contributions.

How do I enjoy my money, while saving for my future?

How do people stick to a savings plan, without having to sideline life?