What have you been working on in your life? A personal habit, a physical achievement, a career goal? If you're having trouble finding the motivation to do something, perhaps it's because motivation is not the same as inspiration.
Motivation is the reason (or justification) we create to convince ourselves to do something we quite often don't really want to do: We're supposed to exercise, because the doctor said so, but hate going to the gym. We're supposed to eat more fruits and vegetables because we need to lower our cholesterol, but can't stand eating bland food.
Inspiration, however, comes from within: our inner voice that knows the answer, breaking through the noise of our habit-mind. For example, how you get exercise is a vastly personal choice with limitless possibilities. Lacking the motivation to go to the gym, and beating yourself up about it, reinforces a feeling of failure and inadequacy, and certainly doesn't help your health. Giving yourself the space to wonder why you don't feel motivated to go to the gym, allows you the space to find the answer. For example, it may simply be that exercising at a gym isn't for you.
Allowing inspiration a chance to develop, let's take this further: perhaps you don't like the crowded atmosphere of the gym, but suddenly remember how much you used to love playing racket ball, and what a great form of exercise that is. Perhaps you love eating at that one restaurant down the street, and suddenly realize you can search the web for easy and healthful ways to replicate those recipes.
A lot of us don't give ourselves the time to just sit and listen to ourselves. If we've got 10 minutes, we're surfing the web, or have switched on the TV. If we do sit down with no distractions, our mind races with all the tasks we haven't yet accomplished, things we've forgotten to do, or things we think we're supposed to do. That doesn't make us feel great, so we quit too soon.
By sticking with it a few times, we discover one of the many gifts of meditation: by allowing this mental traffic the freedom to run and jump, it can get the rowdy out. The more regularly you give yourself the space to just be, the quicker this habit-mind energy will run its course, and your thoughts will begin to slow down. That's when inspiration occurs: when the playing field is open and clear, and you are relaxed.
The next time you're having difficulty finding the motivation to do something, first make sure that it's an appropriate, healthful goal, and that there's no outside pressure behind it. If it is good for you, but you're still having difficulty, perhaps you simply just need some inspiration from within to make it uniquely yours. Give yourself the space to be inspired!