Here's a brilliant quote I came across today from William Law:
Would you know him who is the greatest saint in the world? It is not he who prays most or fasts most; it is not he who gives most alms; but it is he who is always thankful to God, who receives everything as an instance of God's goodness and has a heart always ready to praise God for it.
If anyone would tell you the shortest, surest way to all happiness and perfection, he must tell you to make a rule to thank and praise God for everything that happens to you. Whatever seeming calamity happens to you, if you thank and praise God for it, it turns into a blessing. Could you therefore work miracles, you would not do more for yourself than by this thankful spirit; it turns all that it touches into happiness.
Quoted by Robert Atwell in Celebrating the Saints, page ii.