im 39 years old scared of dying at 40yrs old cause of my weight

You CAN stop yourself. You just haven't yet.

When you reach for a snack, drink a glass of water instead, take a walk, do something else instead.

Consider, WHY you reach for more snacks. Is this emotional eating? Some of us eat when we're bored or sad. My husband eats when he's tired and cannot nap or sleep.

Only eat when you're hungry. Some people like to chew gum between meals. If that helps, great. If you really never feel full, you may have a medical condition. This is a real thing, but very rare. Talk to a doctor.

With the exception of those who actually have a medical condition where they never feel full, the way we think guides the way we eat. Consider what is on your mind when you start munching, if it isn't actual hunger, examine it. Disordered eating can be treated. Have you tried talking to someone about it?

Coming here is a step in the right direction. You see the potential for future problems. Now you have to choose what you will do about it.

Don't expect overnight changes, it has taken years to get here, it will take time to change.