The thought occurs that thankfulness would make an excellent self-measure of sanctity.
Being thankful at all is a great way to start. I don't think a person can be both thankful and covetous at the same time; you can't really hold what you have and what you want together in your mind. Thankfulness implies a kind of restfulness, a pause (however temporary) in concern for tomorrow, and as we know tomorrow is God's concern, not ours.
Being thankful for what's good in bad situations is even better. Nobody likes a Pollyanna showing up to spoil their misery, but the truth is, if things could be worse (and for most of us most of the time, they could be (and often enough will be)), then there is some good for which we ought to be thankful. Genuinely thankful, too; there's no such thing as being thankful grudgingly.
There is such a thing as giving thanks grudgingly, though. This is fortunate, since giving thanks grudgingly is how a lot of us learn to give thanks, as a few minutes in the presence of a child being taught manners will show. Thankfulness is a virtue, a habitual disposition of soul that can be developed through acts of thankfulness, just like the disposition to kindness can be developed through acts of kindness.
The highest form of thankfulness, found among the great saints and not much looked for by the rest of us, is being thankful for the bad things that happen. Not because the saint is wicked and deserves punishment, but because he knows "that all things work for good for those who love God, who are called according to his purpose." Suffering has been sanctified by Christ on the Cross; Christians know, and Christian saints believe, that our suffering is an evil permitted by Providence to draw us closer to Jesus and therefore deeper into participation in the Divine Life.
Though you may not do moral evil that good may result, you certainly may endure natural evil in the Christian hope of the good that will result. In fact, that's by far the most sensible reaction to the natural evils we necessarily face, but few of us are holy enough to be that sensible.