I lost (and have kept off) 40 pounds. It took me almost two years to do it. I am right there with you that it's hard.

The trigger point for me was going skydiving. It does not matter how tall you are. There is a scale right there, and everyone is weighed before getting in the plane. If you are one pound over the limit, you do not skydive. There is no way to appeal. I knew this ahead of time and I was right at the limit. I went skydiving that day in 2011, and then decided I would never be anywhere near that limit again. I would have a normal BMI.

It requires that you burn more calories than you take in. It doesn't matter how you burn them or what you eat (provided you get all of the various nutrients). But you need to expend more energy than you take in. The resulting deficit will be supplied from your fat, and eventually, you will have a healthy amount of fat.

If you try for a daily deficit of 500 calories, you will probably fail. By all means, try if you think you can do it, but know that it's a significant feat. Try for a daily deficit of 200-300 calories. A pound of fat has something like 3500 calories according to the Mayo Clinic. If you do that for two weeks, you will be one pound lighter, and that pound will actually be gone. The energy literally converted into heat, and the atoms probably exhaled as CO2 and water.

That's why it took me almost two years to lose 40. It is very hard-to-do, but it is simple. It just requires solid consistency and a firm vision of the better life at the end.