The danger of living a disciplined life is that we give into the illusion of control. We cannot control outcomes, only how we respond to them. While the Bible calls us to live disciplined lives, we must leave room for God. The author of Proverbs 3:5-6 points that out well. It's a familiar passage we often forget.
You're not God
You cannot conceive of everything. Only God can do that. A big part of life is doing our best and leaving the results to God. You do everything right and have it blow up. At such times we try to figure out why, and we can't. Sometimes we bomb and everything works out too. Such reminds us that we're not God. We don't always understand what is going on, but we do know that God is at work.
Why ethics doesn't work
In studying the great works on ethics my class came to the conclusion that ethics as off because it's trying to figure out right and wrong apart from God. In all our ways need to acknowledge him. When we don't, things could go wrong. Hubris is the term that comes to mind. For example it was said that not even God could sink the Titanic.
Proverbs isn't warning us from action, but giving us wisdom to act. We must engage in life. Yes we may succeed or we may fail, but we must act. We must live. Again, the purpose of living a disciplined life is to be at our best to love others. That fulfills the greatest commandments. It means that when life is hard and not fair that we also rest knowing that God is at work. Act, plan, be disciplined, but remember to leave room for God.