Start by doing knee pushups. If you can do more than 20 of these then they are too easy for you and you should do full pushups.
We want to start slowly to avoid injury, the first two weeks you will only do this workout once a week: do as many pushups as you can without rest (a set) rest 2 minutes repeat two more times (three sets total)
If your joints and muscles feel ok, you can slowly increase the frequency and duration of your pushup workouts until you are doing pushups 3x/week for 20minutes. When you get to the point where you can do more than 20 pushups in all your sets, then its time to move on to a more advanced workout. Please see my website for some suggestions.
The reason many people dont get started in bodybuilding is that it seems to complex and intimidating, thats why I recommend starting out with just pushups and with daily walking (10-30min). Its an easy program, you start feeling better immediately, and your brain starts to associate exercising with feeling good. A recent study showed that as little as 10min of exercise a day can do wonders for you mind and body. Once you brain has made the connection between exercise and feeling good, motivation is no longer a problem and you will find yourself wanting to add new exercises.
If you are overweight and can only do 3 knee pushups, dont be discouraged, its not the number of pushups you can do that is important but the effort. For those of you who are overweight, think of it this way, you are lifting far more weight in your pushups than your lighter counterparts so its natural that you cant do as many pushups. What is important is that you make progress each week, if you did 3 knee...