LMGTFY:
https://www.google.com/search?gl=us&hl=en&q=why+exercise+doesn't+help+weight+loss
Convince yourself.
Not much calorie burning is under our voluntary control. Most of it is automatic. That's why CICO doesn't really work well: Calories Out can't be known with precision. You can weigh your poop, but that's not good enough.???? Exercise might make you eat more calories, negating the little you burned during exercise.
Eat less, and your body will just burn less to preserve your weight. Big source of frustration for dieters: they suffer hunger without much results on the scales. Eat even less and hunger starts to become intolerable, and hunger wins. The best way out of that problem is a diet that helps you avoid hunger: low carb.
Not to deny that enough counseling, sacrifice, and discipline can achieve results. E. g., Weight Watchers, one of the oldest and most successful diets of them all. We don't like to talk about WW here, though. It means spending money. Better to stay fat and medicated, living that short but happy life.
I never advise very overweight people to exercise, except for slow or moderate walking, and I wince when I see them bouncing on the treadmill in the gym. They probably don't know the true condition of their cardiovascular systems, and all that weight on their joints ain't good. Best lose weight first, get a checkup, then ease into fitness with safety.