Persistence is perhaps the most important psychological characteristic that can help one keep moving forward on a project. Brilliance is important, but persistence is key.
One must keep grinding forward, even at times things don't seem to be working well.
Persistence, however, does not mean beating your head against a wall. Persistence can recognize times that force and effort are less useful than others. In particular, if things aren't going well, and you don't easily see where to go, persistence does not mean pushing forward blindly, it just means to keep the effort going in the attempt, while you seek out the best possible path.