I have been afraid to think big. I see this as a common ailment of the mediocre. We fear sacrifice. We fear the cost. We fear discomfort. We fear failure.
I am reading The One Thing: The Surprisingly Simple Truth Behind Extraordinary Results by Gary Keller. Chapter 9 claims that the idea that "big is bad" is a lie.
This book is not from a biblical perspective, but (as usual) anyone who hits on something true hits on God's truth. The main idea is that our mindset (the bigness of our thoughts) determines our actions, which determine our outcome.
Our limits are the ones we place on ourselves. Aside from the reality of my physical and mental limitations, this principle works in the natural word. But it is even more potent in light of God's promises!
The connector to this mindset is faith. Do I believe that I really have access to the abundant grace of God that empowers me in all things at all times to succeed in what he wants me to do? If we believe this, we will BOLDLY OBEY ALL that God has said. And then there will be AMAZING results.