And thou, Solomon my son, know thou the God of thy father, and serve him with a perfect heart and with a willing mind: for the Lord searcheth all hearts and understandeth all the imaginations of the thoughts: if thou seek him, he will be found of thee. 1 Chronicles 28:9. RC 301.1
You should keep off from Satan's enchanted ground and not allow your minds to be swayed from allegiance to God. Through Christ you may and should be happy and should acquire habits of self-control. Even your thoughts must be brought into subjection to the will of God and your feelings under the control of reason and religion. Your imagination was not given you to be allowed to run riot and have its own way without any effort at restraint or discipline. If the thoughts are wrong the feelings will be wrong; and the thoughts and feelings combined make up the moral character. RC 301.2
When you decide that as Christians you are not required to restrain your thoughts and feelings, you are brought under the influence of evil angels and invite their presence and their control. If you yield to your impressions and allow your thoughts to run in a channel of suspicion, doubt, and repining you will be among the most unhappy of mortals.... RC 301.3
Man has been placed in a world of sorrow, care, and perplexity. He is placed here to be tested and proved, as were Adam and Eve, that he may develop a right character and bring harmony out of discord and confusion. There is much for us to do that is essential to our own happiness and that of others. And there is much for us to enjoy. Through Christ we are brought into connection with God. His mercies place us under continual obligation; feeling unworthy of His favors, we are to appreciate even the least of them. RC 301.4
For all that you have and are, ... you are indebted to God. He has given you powers that, to a certain extent, are similar to those which He Himself possesses; and you should labor earnestly to develop these powers, not to please and exalt self, but to glorify Him.... RC 301.5
This earth is the Lord's. Here it may be seen that nature, animate and inanimate, obeys His will. God created man a superior being; he alone is formed in the image of God and is capable of partaking of the divine nature, of cooperating with his Creator and executing His plans.... How wonderfully, with what marvelous beauty, has everything in nature been fashioned. Everywhere we see the perfect works of the great Master Artist. The heavens declare His glory; and the earth, which is formed for the happiness of man, speaks to us of His matchless love.... I call your attention to these blessings from the bounteous hand of God. Let the fresh glories of each new morning awaken praise in your hearts for these tokens of His loving care.—Testimonies for the Church 5:310-312. RC 301.6