"Physicians and nurses should encourage their patients to be much in the open air. Outdoor life is the only remedy that many invalids need. It has a wonderful power to heal diseases caused by the excitements and excesses of fashionable life, a life that weakens and destroys the powers of body, mind, and soul. MH 264.1"
"A merry heart doeth good like a medicine: but a broken spirit drieth the bones."
The EGW passage advocates for outdoor life as a remedy for ailments, while Proverbs 17:22 speaks of the healing power of a merry heart. Both passages connect emotional/spiritual state with physical health, although the specific remedies differ.
"How grateful to the invalids weary of city life, the glare of many lights, and the noise of the streets, are the quiet and freedom of the country! How eagerly do they turn to the scenes of nature! How glad would they be to sit in the open air, rejoice in the sunshine, and breathe the fragrance of tree and flower! There are life-giving properties in the balsam of the pine, in the fragrance of the cedar and the fir, and other trees also have properties that are health restoring. MH 264.2"
"The heavens declare the glory of God; and the firmament sheweth his handywork."
Both passages highlight the positive impact of nature. The EGW passage focuses on the healing properties of nature, while the Psalm speaks of nature revealing God's glory. There is a clear thematic parallel.