According to an article in The New York Times, the act of smiling can promote good feelings. Writer Daniel Goleman cites experiments in which researchers found that saying the word cheese caused a person to smile, which in turn created pleasant feelings. On the other hand, saying the word few created a different facial expression, which resulted in negative emotions.

Interesting as such a study may be, there's a better way to have peace and gladness. It works from the inside out, not from the outside in.

In Psalm 4, David set forth several courses of action he took when he was feeling deeply distressed. He asked God for relief and mercy (v.1). He took comfort in knowing that he was favored by Him and that the Lord heard him when he called (v.3). David was quiet before God (v.4). He did what was right and put his trust in Him (v.5). He rested in the assurance of God's peace and safety (v.8). David was confident that he would receive gladness in his heart (v.7) as a gift from God, not as the result of some forced smile that might bring a temporary good feeling.

Father, help us in our low moments to look up to You. Grant us the peace and gladness that David experienced when he called on You.  —MRD II  — Mart De Haan