Sounds like you're going through the same thing many of us do, I know I went through it. You received good advice so far & now I'll give you my two cents.
I've been building mine for almost 6 years now. I've had a lot of help from 3 of my friends & this forum. Without those things, I don't know if I would be so close to finishing mine. However, I did feel the same way as you early in my build but soon realized some things:
1. If this was easy, everyone would do it.
2. Take time to look back at pictures of what you have accomplished.
3. Think of your build as a valuable learning experience.
4. Stay focused on your ultimate goal. For 25 years,I wanted a Cobra so I had something Cobra related in plain view in my house to help me focus on that goal. I believe in visual cues.
5. Don't set completion goals as I did, since many times, other more important things get in the way that caused me to miss that goal, thats when the frustration sets in.
I try to look at it this way: Building a Cobra is like eating an elephant, you got to do it one bite at a time.
Even though it has taken me almost 6 years, I hope to have many more years than that to enjoy my Cobra.
So, stay focused on the prize, enjoy your accomplishments, have fun & press on one bite at a time.
Randy