Quoted from Absolute Honesty by Larry Johnson and Bob Phillips
If you always tell the truth, you never have to conjure up excuses or backpedal on your explanations.
By keeping things simple and honest, you free yourself of the worry about being caught in a lie and the consequences when you are. You create trust among those around you. You strengthen relationships. You reap the benefits of doing the right thing. You discover that the discomfort of being honest is rarely as unpleasant as the pain caused by deceit. You avoid paying a high price for lying. Through the practice of real-time honesty you live and work in the present, neither haunted by lies told in the past nor fearful of having to "pay the piper" in the future. Those are the benefits of telling the truth.
All of us make mistakes. Lying about those mistakes almost always makes the situation worse, not better. It not only impeaches our credibility, but it insults those to whom we have lied.