We all have different starting levels.
Since I'm focussing on getting into shape with this blog right now, let's assume a fairly beginning level.
You might be 40 pounds overweight, or 140. You might not even know. You may have worked out a lot in the past and just lost it, or this whole idea of physical culture is new.
But a few things are likely to be true:
You likely have some health problems from overweight. The most common of these that are relevant to my type of program are knee and back issues (and feet, sometimes), higher blood pressure, and breathing issues.
While I'm not able to give medical advice, it's likely your doctor will agree that all of these will be alleviated to some degree by losing weight and improving your muscular/endurance health.
How do you start? Well, soon enough you want to sweat. But for a very beginning level all we want is movement.
So let's start with the first three things- pushups, abdominals, and squats.
I highly recommend a book called "convict conditioning" for this type of program, it has very good examples of working up your levels in these areas. I don't tend to agree with the workout programs themselves, though.
Ask yourself, can you do 15 pushups, nice and slow, on the ground? It's okay if you can't. you can start by leaning against a wall, a bit lower would be a countertop. a step stool would be the next progression. Eventually you will get to the ground, so don't worry. You don't want to kill yourself, and we'll see why a bit further in.
Abdominals are an area where there is a lot of controversy. Some people think situps are bad for you, some think crunches are bad for you. I don't think it matter much what you are doing, if your form is right. But follow whatever professional advice you can get. (ask your doctor.) - But I would start with leg lifts.
Depending on how much extra weight you are carrying, you may or may not be able to move in certain ways. but, lying on your back, you can get your legs in the air somehow. Pick your starting level, one leg at a time or both, knees bent of legs straight. just lift them up and set them down- higher is better. GO slow, and don't flop. half the exercise is in slowly lowering your legs. You want to do this 15 times (or 20 if you are alternating legs)
Squats are a problem area, because knee issues are so often a problem when overweight. There are two ways to approach this, with the caveat that you need to be cleared by your doctor, expecially if you have known problems.
One is to lie on you back with your hips elevated (a cushion or pillow can help.) Get your legs vertical above you and do the squats that way. Another is to start with half squats, with your hands on a counter top. Eventually you should work up to being able to do full squats nice and fast, but that's later.
Again, you want to do 15.
Now, the key here is you do this set of 3 exercises often. 5, 10 times a day. you need to make sure you progress to a level where you are feeling effort as you improve. And stay with your weight. (don't blow your knees trying to do deep squats 150 times a day when you are still 320 pounds)
You will elevate your heart rate a bit, keep the juices and metabolism up.
Not a complete workout plan- walking or running or cycling or swimming, kettlebells or weights- there's plenty to add. But if you are starting from a really low place, it's far better than not starting.
Advancing in this is possible through 3 methods, which you can combine at will:
1: Adding exercises (again, see the convict conditioning book and look at other bodyweight exercises)
2: Adding repetitions (you may find you need to get these interval workouts to take 6-10 minutes to get your heart rate up some)
3: Increasing difficulty.