Nothing worthwhile comes without hard work and persistence, Rick Warren has said, and Christians must not let the Enemy discourage them from working for God's purposes.

In a blog post on Thursday, the bestselling author and pastor of Saddleback Church in California says: "There are many things that work to keep us from completing our life missions. Over the years, I've debated whether the worst enemy is procrastination or discouragement. If Satan can't get us to put off our life missions, then he'll try to get us to quit altogether."

When we are discouraged, Warren says, we become ineffective, and "work against our own faith".

"When we're discouraged, we're saying, 'It can't be done.' That's the exact opposite of saying, 'I know God can do it because he said...'"

He urges readers to ask themselves how they handle failure, whether they are persistent, or get grumpy and frustrated when things don't go their way.

"If you're discouraged, don't give up without a fight. Nothing worthwhile ever happens without endurance and energy," Warren says. He refers to chapter six of Paul's letter to the Galatians, where he says: "Let's not get tired of doing what is good. At just the right time we will reap a harvest of blessing if we don't give up".

"When an artist creates a sculpture, he has to keep chipping away. He doesn't hit the chisel with the hammer once, and suddenly all the excess stone falls away revealing a beautiful masterpiece. He keeps hitting it and hitting it, chipping away at the stone," Warren countinues.

"And that's true of life, too. Nothing really worthwhile ever comes easy in life. You keep hitting it and going after it, and little by little your life becomes a masterpiece of God's grace.

"The fact is, great people are really just ordinary people with an extraordinary amount of determination. Great people don't know how to quit."