Easiest way is to swap your diet. Try drinking water instead of sugary drinks, eat as you normally do but if your eating a sugary/fatty/meal full of carbs just lower your portion size. Try squeeze in excersise wherever you can, e.g. working to college/school, or if you get dropped off ask to be dropped off a bit far. Go out into the city centre e.g. and just have a walk around.
Of course, if your looking for a way to lose weight properly, then excercise and a diet plan will be needed. I would recommend doing some research online and investing in a proper one. Personally I would recommend you search up "LDNMuscle", they offer a range of plans for losing weight, gaining muscle etc. for men and women. They give meal ideas as well as excersise routines, and yes, you get cheat days etc.