Moses
Moses made a great mistake. When he looked upon the bondage and oppression imposed upon the Hebrews (his own people) by the Egyptians, he killed an Egyptian (Ex. 2:11-12).

Moses' heart was right, but his actions were wrong. That's the way it is with a lot of people. They attempt to fulfill their calling, but they don't get the wisdom and knowledge of Go on how to do it.

As a result of this sin, Moses fled to the backside of the desert and spent 40 years there. It looked like it was over. Moses at 80 years old was tending his father-in-law's sheep. But his calling wasn't over, because "...the gifts and the calling of God are irrevocable" (Rom. 11:29). This means God never pulls them back.

God called Moses to do something. Moses made a mistake in how he was to do it, but the day came when he saw a burning bush that wasn't consumed, which represented God saying, "I'm going to light the fire in your heart again, Moses, and this time, you'll not go in your own ability. You'll go in My power, strength and wisdom to deliver the Children of Israel out of Egypt." (Read Ex. 3:9-14).

Moses messed up, but God gave him another opportunity to fulfill his call. If you've messed up, repent. The accept God's grace and stand up on the inside! You can still fulfill that which God has called you to do!

Joshua
Another person who had his calling delayed was Joshua. Joshua knew he was to lead the children of Israel into the land of Canaan. Joshua and Caleb were in agreement that they could take possession of the land. They said, "We are well able to possess it" (Num. 13:30).

Joshua's heart was right, he had the right plan, but the people around him didn't understand. They sinned against God. Joshua's call was delayed because of the mistakes of other people.

The day came when God said to Joshua:

...Arise, go over this Jordan, you and all this people, to the land which I am giving to them-the children of Israel.

Every place that the sole of your foot will tread upon I have given you, as I said to Moses.

From the wilderness and this Lebanon as far as the great river, the River Euphrates, all the land of the Hittites, and to the Great Sea toward the going down of the sun, shall be your territory.

No man shall be able to stand before you all the days of your life; as I was with Moses, so I will be with you. I will not leave you nor forsake you.

Be strong and of good courage, for to this people you shall divide as an inheritance the land which I swore to their fathers to give them.

Only be strong and very courageous, that you may observe to do according to all the law which Moses My servant commanded you; do not turn from it to the right or to the left, that you may prosper wherever you go.
(Josh. 1:2-7)

You may feel like you're in the desert because of the mistakes of other people. You may be thinking, "I'd be in the ministry right now if it hadn't been for this, that, or the other." 

I've got good news for you: you can still start over! If there's something the Lord has told you to do, but it has been delayed, today is the day to receive God's grace and begin again.

Source: From You Can Start Over by Billy Joe Daugherty
Excerpt permission granted by Harrison House Publishers