The Sage, Nachum Ish Gamzu (the teacher of Rabbi Akiva) is famous in the Talmud as the leading exponent of this insight.  His invariable reaction to whatever befell him, even to seeming disaster, was: gam zu le-tovah – “this too is for the best.”  Even what appears to us to as the worst is not really bad at all; it is in reality good, for its purpose is good.  A person suffering from a mortal disease is glad if he can undergo an operation which may save him, however much it may hurt.  This is how we must understand God’s ways.  But in this case the good is incomparably greater – unimaginably more sublime.  ~ R’ Eliyahu Dessler zt”L