The only thing we need do is speak truth whenever we speak. The light of truth will take it from there. Consider for a moment how often in our lives we have not spoken truth in a matter. Why would that be? Are we not children of the Almighty Living God who does not speak lies? Do we not follow our Lord Jesus Christ who came in all graciousness and truth? Are we not to imitate Him whereby we would also speak truth?
Whatever the fearful situation you would be in that would impend a lie across your lips, you need only speak the truth of the matter still. Whatever burden that may be upon you will be relieved. The truth sets you free and it is with truth that we defeat our fears.