You ask "How do I Live ONLY IN THE SPIRIT?"
Apparently, this will solve all my problems in life.
Paul compares "walk by the Spirit" and "works of the flesh" in his letter to the Galatians:
Galatians 5:16-18 But I say, walk by the Spirit, and you will not gratify the desires of the flesh. For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do. But if you are led by the Spirit, you are not under the law.
Galatians 5:19-21 Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.
Galatians 5:25 If we live by the Spirit, let us also walk by the Spirit.
God allows bad things to happen to His people to test the validity of their faith, to determine if their faith is a lasting faith, to determine if it's a destructible faith. Because if it's a destructible faith, it is not a saving faith.
Saving faith is indestructible, enduring to the end. Saving faith perseveres. Hezekiah was being tested in 2 Chronicles 32:31 and it says, "God left him to test him that he might know all that was in his heart."
God abandoned Hezekiah so that Hezekiah could see what he was really like when left to himself. It wasn't that God needed to know what he was like, God knows that. A true saving faith will pass that test.
Read Hebrews 12:10-11.
The way to never be disappointed in this life is to make sure that your preoccupation is in the life to come.
The good news is when we are born again, we are washed clean of all our sin, we are new creatures in Christ, and Jesus is Lord. Praise the LORD.