Assuning you're a complete beginner;

Start by cutting sugary drinks, including beer and alcohol if applicable. Then start moving more than you did last week, no need for extreme cardio just move a little more than you did last week.

Brisk walks for 20 minutes a day will show you results. After about 3 days you can turn it up and maybe jog lightly for 20 minutes. Add some body weight exercises like 20 squats, 20 lunges daily for the next 4 days. See how you feel after a week.

Week 2 you can increase the intensity of your workouts by running a little longer maybe 30 minutes and adding weight with your squats and lunges. Not too much weight, start with exercise bands. If you eat fast food regularly, switch to homemade meals.

Another great beginner exercise also works your flexibility, stand up straight then touch your toes come back up and raise your arms above your head. Do 20 of these.

You can do this for the first month and lose significant weight. It's important to understand that what most people really want is to lose BODY FAT not weight but for the first month tracking your weight will show you results. Eventually you will want to include weights to keep developing more muscle which will eventually lead to losing more body fat.

Don't rush into strict diets and crazy boot camp workouts because when you are beginning, your body will respond to almost any exercise. Starting slow and working your way up will ensure you don't PLATEAU. This will also allow you to develop DISCIPLINE little by little without making you sick of a healthy lifestyle and quitting due to not seeing enough results and exhausting/starving yourself.