Some of the men that volunteered for David’s army could shoot their bows with their right hands or their left. That’s bad news for the opposing team. But it could potentially cause problems for David’s army too. 
Here’s how: 1) the ambidextrous sharp shooters could become so proud of their skill level that they would begin to think that they didn’t need anyone else to battle 2) the other warriors could put so much trust in the men that they would leave them to fight alone 3) the other warriors would leave their shields behind and try to become shooters; leaving no preparation team or defense for their army. 
Have you ever thought of leaving your calling behind so you could chase someone else’s? Maybe you have thought so much of yourself that you feel no need to acknowledge the other’s God has blessed you to serve with? Or maybe you feel like there are enough people out there working for the Lord so you can just take it easy? 
You, just like others, are chosen for the ministry God has given. We are wanted, needed and effective where we are. Bring God glory by devoting yourself to his cause and he will bless. 
Scripture taken from:

I Chronicles 12:2