Moses argued with God that he didn't have the necessary skills to accomplish what God wanted. What human alive does? Jonah choose to disobey and went the opposite direction of his task and ended up in the belly of a fish (I think I am safe since I live hundreds of miles from any major body of water... then again?) It seems God puts us in situations that are impossible without relying on Him. "Trust Me," He says gently. "Trust Me," he repeats in a small gentle voice. Can it really be that simple? Yes, but what muddies the water is our old self, our old nature that always seems to use logic and past experience to tell us - "That's impossible!" But with God all things are possible (Matthew 19:26). There needs to be a disclaimer here. Make sure God has called you to do the task before you because without Him, you can do nothing.
So press on, knowing that God has called you to accomplish certain tasks for Him that He asks no one else to do. You have the specific abilities and talents (which He gave you) to get the job done. You need to constantly remind yourself of that very Truth. It is God who has called you and equipped you to do the work He has assigned you. Who is the Master here and who is the slave? God gives out the job and you have to faithfully serve Him.
SCRIPTURE READING
Exodus 3, Jonah 1, Matthew 17:19-21, Matthew 19:25-27, Romans 8:28-39, 2 Peter 1:3-11
BOTTOM LINE
We are slaves not employees. We don't get to apply for a new job just because the old one doesn't suit us.