As in... you look at how much work you still have left to do... and think about the $$$ you'll need to spend to get there... and how much time it will take to make real progress... and your brain starts to swell... and the thought that forms in between your ears is a 100 db scream of: "What the F-$-&-K have I gotten myself into???"
Sometimes. But I just walk away and time lets me chill. If you want to get finished, Keep your eye on the prize - not the journey to it. It's about the journey, but I find concentrating less on the time and treasure and more on the end goal helpful.