true happiness part 1: don't believe in yourself

At the beginning of Matthew 5, Jesus describes what being blessed is like. Blessed could be translated as happiness but if we want to do that, then we need to think deeper than the fluctuating happiness that is dependent on our circumstances. True happiness is not found in what is happening around you but it is a gift of God, it is God's favour shown towards you, God's approval given to you. Jesus is going to describe what this true happiness looks like, and it's a bit different to we might expect.

Matthew 5:3
Blessed are the poor in spirit, for theirs is the kingdom of heaven

To be poor in spirit is to recognise our own sinfulness before God, to have no confidence in our own ability to make ourselves acceptable to God and to admit that we need help because we can not sort it out ourselves. This is the starting point for understanding and recieveing the gospel, entering into the kingdom of heaven, and finding true happiness.
The advice of the world is to have a bit more self-esteem but this places a crushing load on your back as you repeatedly fail to meet the standards you have set for yourself, let alone those God has declared. The church doesn't tend to do much better, holding up religious performance and external efforts as the way to enter the kingdom of heaven, again putting the focus onto ourselves.

Confessing our own failure and relying on Jesus performance, not ours, brings freedom, life and a happiness that is not dependent on whether we have had a "good" or "bad" day.

Matthew 5:4
Blessed are those who mourn, for they shall be comforted.

Surely mourning can not be part of true happiness? Jesus says it is. Those who mourn take their own sin seriously, take other peoples sin seriously and are greived by a sinful broken world. The world might tell us to ignore this as much as we can but when life goes wrong, things start to fall apart and we end up crumbling in despair or deluding ourselves that everything is ok.

For godly grief produces a repentance that leads to salvation without regret, whereas worldly grief produces death.  2 Corinthians 7:10

True happiness and true comfort is found in taking sin seriously and taking it to the cross. It is found in repenting and knowing our sins are forgiven, knowing that the sins against us and those we love can be entrusted to the one who judges justly (1 Peter 2:23) and knowing that one day "[God] will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away." (Revelation 21:4)