Fat loss means burning more calories than you eat. Some people need to exercise to make that happen, others don't. So really it's up to how you eat. There's people who get so fat they physically can't exercise or even walk around until they lose 100+ pounds. They start their journey with a healthy diet and if they continue they'll eventually be able to exercise again.
If your weight has been steady then do a calorie count for a few days to figure out an average per day. Then you can adjust down with a healthier diet.
Exercise never hurts and can help burn a few hundred calories. It also gets your body, including your heart, into better shape and can force your metabolism to burn fat. People who exercise a lot typically have a lower resting heart rate which is obviously good.
You can always talk to a doctor, dietician, personal trainer, or all 3 to get help setting up the best scenario for you. After that you've just gotta put in the effort.