There was a post that circled the internet years ago with an idea that I find helpful. It went something like this:
When I'm afraid to take up a challenge or overcome an obstacle, I close my eyes and imagine that I'm an 80 year old who regrets not overcoming the obstacles or attacking the challenges I desired to throughout my life. Then, when I feel sufficiently disappointed, I say to myself, "I wish I were young again," and then I open my eyes and huzzah! I'm young again!
When obstacles pile up, or maybe it's just one huge one, it can feel so daunting and motivation can wane. The first step, if this is the case, is to find a way to intrinsically inspire yourself to start working on finding or accomplishing the solution.
Maybe it's that the challenge seems way above your capability. However, while it may be above your capability at this moment, that's only because you haven't taken up the challenge before. Once you make it to the other side, the next time a similar obstacle presents itself, you'll be thinking to yourself that you've conquered that before, and you learned a few lessons along the way. You will find that you can approach a comparable difficulty with more confidence and motivation gained from your knowledge and experience. Each mountain you climb will build the knowledge to help you with the next one.
What methods do you use to motivate yourself? What proverbial carrot do you dangle out in front of you? What obstacles have you already overcome in life that lend you knowledge, experience, and hope for overcoming the next challenge?