Motivation is about goals, so set yourself a goal or two - something that you can achieve - nothing off the scale like loosing two stone in a week - and work owards your goals.The well-being that is inherent in working towards, and then achieving a target, will assist your overall motiovation, and once you see and enjoy the results, you can expand the system to other areas in your life. You don't specifiy the areas in which you need motivation - maybe you can share your tasks with a friend? Have a go, and feel better fairly quickly once the results start to show. Remain focused, keep your discipline, and you will get there.