Trying to lose weight or exercise effectively by yourself or with a friend who is in similar shape is fine if you are looking to lose a few pounds. If you are serious about making life changing differences then you need to change your approach.
The first step is to adopt the correct mind set and acknowledge via self analysis that something in your present life is "wrong". Once you have identified this, accepted it and changed it, only then should you move on to step 2. Without completely conquering step 1 the following stages are doomed to failure, they have little chance of success as your mind set is not correct and as a result your dedication & commitment will falter.
The second step is to join a gym, hire a trainer or find a training mentor who is prepared to share their time and experience. If finance is a problem DVD's are an option or the internet is packed with training routines, programs and advise. You need to make sure you exercise with someone who is fitter, faster or stronger to ensure you "get the bug" and become competitive.
The third step is to set targets or goals. These should not be weight orientated but exercise targets (10km run, completing a workout program, lifting a target weight etc). Your entire focus then becomes your training goal, once one goal is reached you set another and the process repeats itself.
The video clip below is an excellent example of completing a workout program. The Insanity routines is an intense cardio routine which will get results, but only if step 1 is completed first. Watch the clip, use it as motivation and change your life.......