"Never flag in zeal, be aglow with the spirit" (Romans 22:21, RSV) .
You can't tell how much you can achieve until you try...
Often times in our lives we are faced with the temptation to quit just too soon. Man is naturally impatient, but success in life depends on one's ability to overcome this weakness. Many people throw in the towel just when the battle is getting warmed up! This is a basic tragedy of the human life.
If we are going to amount to anything in life, we will have to learn to stick out our neck a little longer than normally necessary. David killed Goliath not because he was the strongest or most militarily skilled Israelite, (he wasn't even considered fit for the army), but simply because he dared to try. There were over 32,000 able bodied men that made up the Israelites army that day and each of them had the potential to kill Goliath, but none of them made an attempt. All God was looking for was someone to step in and step up. He was waiting on someone, anyone to step into the square and challenge the giant!
There is no telling how many battles we have lost, how many opportunities we have missed, how many blessings we have passed up on. All because we failed to try or because we quit.
Don't quit. Don't stop. Keep trying.