Many people act as if pain and sorrow were universally bad. They do so selectively, of course, as pain and sorrow tend to be ignored when the decision that generates them aligns with natural desires. Regardless, the idea that bad is what hurts and good is what feels good is supremely foolish. Those who adopt it will choose to interact with the world in a way that permanently and severely reduces the joy, happiness, and material blessings they can obtain in life.
Even the briefest consideration would show that the meaning of good and bad is not as simple as what feels good and what hurts.
Sorrow is not universally bad. Many painful things are considered good and are not only endured with joy, but sought for: childbirth; training for a successful vocation; weeding a garden. No one chides a mourner at a funeral, and almost every worthwhile thing in life requires toil.
Pleasure is likewise not always good. Many pleasurable things are considered bad, such as taking addictive drugs. Happiness, when based on something false, always ends up causing more pain in the long run than joy in the short term.
Pain and sorrow are not always bad, and pleasure and happiness are not always good. How do we determine when they are good and when they are bad?
The Lord taught that the poor in spirit, those who mourn, those who are meek, those who hunger and thirst after righteousness, those who are merciful, those who are peacemakers, and those who are persecuted are all in a blessed state:
3 Blessed are the poor in spirit: for theirs is the kingdom of heaven.
4 Blessed are they that mourn: for they shall be comforted.
5 Blessed are the meek: for they shall inherit the earth.
6 Blessed are they which do hunger and thirst after righteousness: for they shall be filled.
7 Blessed are the merciful: for they shall obtain mercy.
8 Blessed are the pure in heart: for they shall see God.
9 Blessed are the peacemakers: for they shall be called the children of God.
10 Blessed are they which are persecuted for righteousness’ sake: for theirs is the kingdom of heaven.
11 Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake. (Matthew 5)
In providing these sayings, Jesus is inviting us to reframe our experience.
How can it be that states of suffering can be referred to by Jesus as states of blessing? Because of the outcomes they provide. These particular ways of suffering yield the kingdom of heaven, comfort, inheritance of the earth, fulfillment, mercy, etc. These are blessings, indeed.
Jesus charges us to consider ourselves benefitted from God when we experience these conditions and qualities. He’s charging us to have joy and happiness that derives solely from our adherence to him and our application of his teachings in our actions, thoughts, and desires, no matter what our external circumstances may be.
In the scriptures, focusing on improvement is called living after the manner of happiness (see 2 Nephi 5:27). It is synonymous with being spiritually-minded (see 2 Nephi 9:39). It is opposite to wickedness (intentionally acting against your sincere understanding of what is right) and being carnally-minded (seeking immediate pleasure for yourself vs. long-term benefit for all):
5 For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.
6 For to be carnally minded is death; but to be spiritually minded is life and peace.
7 Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be. (Romans 8)
Notice how what improves is typically not what feels good in the moment. You shouldn’t conflate happiness and pleasure. “He that loveth pleasure shall be a poor man: he that loveth wine and oil shall not be rich.” (Proverbs 21:17) Pleasure is fleeting. It is often short-sighted and selfish. It is inherently fixed on the here and now.
Pain and sorrow are only bad when they result from the consequences of ignorance of God or disobedience to him. Pleasure and happiness are good so long as they occur as a result of adhering to God.