Every time I start working on a fresh new idea, I get really excited and motivated. The first few weeks will be extremely productive as you have momentum and optimism on your side. It's similar to the feeling when you first got a book. You'll go through the first few chapters really quickly. If you're fast, you might even finish it on the same day.
But unlike reading a book, working on an idea and developing it can't be done in a day or two. It's a marathon not a sprint. So what happens when your initial enthusiasm and motivation wears off?
You'll start to be less productive and suddenly everything seems hard. At times, you might even ask if you should continue working on it. You'll start to notice all the flaws and problems with your idea.
My advice is that you have to see it through somehow. Nothing great and worth doing has ever been easy. You'll learn more from finishing it and fail than abandoning it half way.
It is said that failure is the best teacher. I think success is a better one but to get to either, you actually have to reach the finish line. Whether you succeed or fail, you win. You lose when you give up half way.
The only other reason you lose is that you didn't even start. So get started and make sure you persevere till the end.