How many times have you said, "I know I should do this (or that), but if I do, I am afraid this (or that) might happen."
What you need to realize is that it isn't about what YOU want to happen. It's about what God has planned for us.
When you step out of God's Will to do what YOU want to do, instead of what God has commanded you do, you are getting in the way of what God has planned for you.
Yes, there are times when you will say, "This is going to mess up everything I want...but if You say so...". God would rather hear that than, "I have a better plan. Let me take Your place."
If you want to mess up God's plans, He won't stop you, but you won't like it.