If you tell God no because He won't explain the reason He wants you to do something you are actually hindering His blessing. But when you say yes to Him all of heaven opens to pour out His goodness and reward your obedience. What matters more than material blessings are the things He is teaching us in our spirit.
My dad encouraged us to fail. Growing up he would ask us what we failed at that week. If we didn't have something he would be disappointed. It changed my mindset at an early age that failure is not the outcome failure is not trying. Don't be afraid to fail.