Goodness is one of the attributes of God. So, if you want to resemble Him, you must not accept anything that doesn't belong to goodness no matter how small it seems to be. Take 'truthfulness' for an example. If you want to be a truthful person, you should not be satisfied when you stop lying but should actually hate and throw away the deceiving heart that causes you to lie in action. When you come across a situation where you can win benefits by lying, you must not think this is ok but avoid telling even the smallest lie even though it would bring you a great amount of loss. Only then, can you achieve a truthful heart.