The wrong perception and a negative attitude are harmful to our health and steal our joy, which is what the enemy desires. He wants us to be sad and depressed so that we lose hope, but this is not God’s will for us. God's will is for us to rejoice always, both when things are going well for us and when they are not. He wants us to pray continually and to give thanks in all circumstances (1 Thessalonians 5:16-18).
A sad and depressed Christian goes against the command of God and His Word. God commands us to rejoice when we face trials and difficulties; such times should be regarded as testing of our faith. We should rejoice in times of suffering because we know that God uses these trials to build endurance, strong character, and hope within us (Romans 5:3-4; James 1:2-4). At the end of the age, when He returns in full glory, we will be perfect and complete in Christ Jesus.
Paul, while in chains in a Roman dungeon, wrote his final letter urging the Christians to "rejoice in the Lord always" (Philippians 4:4). For God sits on the throne forever, reigning supreme over everything, every circumstance in heaven, on earth, and under the earth (Revelation 4:2). Everything will work together for the good and according to His purpose and will (Romans 8:28).
We should always place our complete trust in God, for nothing—no power or dominion—can stop His will and purpose from being accomplished when we walk in obedience to Him (Isaiah 46:10-11).