well there's the paradoxical question to end all the paradoxical questions and one of the best examples why we cannot run with a verse or a doctrine that emphasizes one thing without weighing in on what appears to be a counter doctrine. this is why we end up with grace/works arguments, law/grace arguments, Calvinism vs Free choice arguments and many more
many people will say the Bible contradicts itself and others will choose what appeals to them and state that is what the Bible says when neither is correct
the long and short of it is that we are never promised the perfect life but we are perfect in Christ
we are never promised perfect physical health but we are promised eternal life
we are never promised wealth but we have all the riches in the world in Christ
we are told that if we follow Christ we may very well suffer hardship as a servant is not above His master, yet we are told that Christ fulfilled all the law in His sacrificial death
we are told to pick up our cross and follow Christ and also told that His yoke is easy and His burden is light
we are told that we might receive nothing in this world but our reward in heaven will be great
seeming paradoxes
obedience requires doing what we know to do that is right and in the Old Testament, the law, comprised of the 10 commandments and at least 613 others if you read through Leviticus, is what was required. break any one of them and a sacrifice was required
there are three kinds of laws in the Bible, moral, civil and ceremonial. all of these laws have been fulfilled in Christ. He was obedient to death.
if assurance of everything going right in our life would be a result of perfect obedience, then surely a Christian could claim that in light of the fact of Jesus fulfilling all that is required in our place?
but as you say, we do not see that. if you read the prophets, you will see they probably suffered more than anyone WHILE they were obeying God
the catalyst or causative force being dealt with is sin. this is a fallen world and the Bible says the devil is the god of this world and apart from the Holy Spirit, is the force people deal with on a daily basis in the choices they make
we choose what we do, how we respond and act, moment by moment and the results of those things are like a chain reaction
I don't think there is a simple answer to your very thoughtful and provoking question