You need to choose the right work out for you. I would recommend a person trainer for at least one month if you have never really worked out before. It is hard to maintain a pattern if you have no clue what you are doing but the easiest and cheapest thing to do is go for a run!
Running not only makes you sweat but it makes your lungs stronger and healthier, it creates blood flow in your body and adds oxygen to your blood. There is nothing bad about running. If you have a dog well there are no excuses for you, take your dog for a long walk or a short run, or do both!
To lose fat and trim your body, a lot of reps on your arms and legs will trim the fat, little reps and a heavier weight will increase muscle. So depending on your body type and what you are trying to achieve you would use this as a guide.
Lose fat and trim body- less weight, a lot of reps
Gain Muscle- a lot of weight, little reps
This is true for anything you are doing whether it be leg raises, push ups, sit ups, crunches, lifting weights etc.
Another thing I recommend you do is a circuit. Circuit training is hard and fast. It will push you until you are finished and each exercise in the circuit can work a different part of your body but it is always fast enough to keep you sweating and breathing heavily.
remember: Losing weight is never easy, it will get easier for you as you go on and get used to the pattern, but it will never be easy. You must push yourself to 1. actually get up and go work out, 2. work out harder each time and finish each work out and 3. to do it every day.
Core: Push ups, sit ups, crunches, lunges, burpees, abdominal twists with weight, running, jumping
Legs: burpees, lunges, running, weight lifts with legs, squats, leg raises
Butt: Leg raises, running, sprinting
Arms: Weight lifting, push ups
Entire body workout: Running, jogging, long fast- paced walk, sprinting, swimming, any sport for a good amount of time will also allow you to have fun but lose weight, boxing, kick boxing, Shayunta Yoga (hot Yoga).
At the end of each workout day, stretch your entire body. This will loosen your muscles and allow for weight loss to actually occur as well as decrease the chance of you having lactic acid build up. This is what makes your muscles so sore you feel like you cannot even walk!
My advise: No matter what you are doing, just make sure you are being consistent. Consistency is key to losing weight. You cannot work out once or twice a week and achieve your goal weight. You must be working out at least 4 times a week for about an hour to two hours.