The world of televangelism is infamous for promising more than they can deliver, promising more than Jesus ever promised, while avoiding the warnings that Jesus also preached. This one-sided message is not the complete message of Jesus. It is an edited version which denies the suffering and self-sacrifice that he modeled for us all.
There are a lot of topics that preachers speak about many of which are helpful, but there is always a central theme which Jesus demands. Repentance and the kingdom of heaven are themes with which Jesus began his ministry (Matthew 4:17) and repentance and forgiveness are themes with which he concluded it (Luke 24:47), saying that this would continue to be preached into all the world. Repentance refers to a continual life-changing experience which begins with an initial change of heart and progresses towards an ever growing life of becoming more like God in every way. When we submit to God, we are forgiven all our past wrongdoings and come under the protection of his spiritual kingdom. We grow less interested in the useless pursuits of this world and more interested in living the way of real joy.
That way of real joy is not a way of selfish pursuits. That is the way to unhappiness. True happiness comes from a life lived of giving it all away. We can't take it with us, so why do we hoard? Rather than lose it all after we die, whereby we have very little control over how it is distributed and used, let us begin giving it all away now. Dear preacher, that's how Jesus wants you to live too and that's what Jesus wants you to preach. He does not want a self-centered, materialistic false gospel of health and wealth, but the words expounded that you will find in a red letter Bible. That's how I understand Matthew 28:20. What about you?