Why do you doubt me?

Great question! I was reading in Matthew 14 where Jesus walks on water after he had fed 5,000 with a few fish and a little bit of bread. Peter gets brave enough to walk to Jesus on the water, and then he looks at the distractions (wind and waves); and his faith begins to waiver and he starts to sink. ---I don't think little of Peter. I have seen God do tremendous things in my own life. I have seen the dead (spiritually) come to (real, eternal) life. I have seen people that were supposed to die (flesh) live longer than they should have. I have seen men get a second chance. I've been among both of those categories. ---So why do I look at the distractions? Why do I doubt? ---Help me Lord to focus on You. I have no reason to doubt, but at times my life shows that I doubt. Why do I...why do we attempt so little for Jesus, when we could walk on water?