If you are burdened and weary, you need not curl up like leaves upon a withered branch. Cheerfulness and a clear conscience are better than drugs, and will be an effective agent in your restoration to health. . . .
You will be benefited with the effort you make to be cheerful. . . . Get out of doors as much as possible, and be benefited with the breezes and the blessed sunshine. Let the songs of the birds and the beauties of nature awaken holy and grateful feelings in your hearts and lead you to adore your Creator who has anticipated your wants and surrounded you with unnumbered tokens of His love and constant care. . . .
Have an aim in life while you do live. Gather sunshine about you instead of clouds. Seek to be a fresh, beautiful flower in God's garden, imparting fragrance to all around you. Do this, and you will not die a whit sooner; but you will surely shorten your days by unhappy complainings. . . .
Prune off every decaying leaf and withered branch from your life and manifest only freshness and vigor.
The cheerfulness of the Christian is created by the consideration of the great blessings we enjoy because we are the children of God. "Therefore, my brethren dearly beloved," he says, "and longed for, my joy and crown, so stand fast in the Lord, my dearly beloved." The cheerful enlightenment of the mind and the soul temple by the assurance that we have reconciliation with God, the hope we have of everlasting life through Christ, and the pleasure of blessing others, are joys which bring no sorrow with them.
Christians should be the most cheerful and happy people that live. ML 177
Whatever your anxieties and trials, spread out your case before the Lord... The weaker and more helpless you know yourself to be, the stronger will you become in His strength. The heavier your burdens, the more blessed the rest in casting them upon the Burden Bearer. DA 329
A merry heart makes a cheerful countenance, But by sorrow of the heart the spirit is broken. Proverbs 15:13 (New King James Version)