If you want to shape up your body and lose fat without going to an expensive gym, then bodyweight training may be the answer for you. In addition, the majority of people out there don't have a lot of time to workout as it is. So, workouts that last more than 30 minutes is completely out of the question.
If you do have a lot of time workout, I personally like short, intense workouts. They keep me on track and I can get back to doing the things I need to do (like work). You also have a lot more time for friends. I have this bodybuilder friend who spends all his free time at the gym, and I can never get a hold of him when I need to.
Getting a quick upper body bodyweight workout is not that difficult. You can create workouts that last anywhere from 5 minutes to 45 minutes. It's all based on how much time you have to workout, or how much time you want to spend working out.
5 minute workouts? Yup, you can create really short workouts by organizing them into circuits and intervals. A circuit is where you perform 2 or more exercises back to back with little to no exercises in between each exercise. An interval is where you perform exercises with a time frame (usually 20-60 seconds), followed by a short rest period.
Recently, I've been training using the Circular Strength Training (CST) method. CST is really complex and difficult to define in a few sentences. The main concept behind CST is all about moving the body through it's full potential of movement.