My suffering is not purposeless.
Locks serve many functions, most commonly to keep a door from being opened... or a treasure chest. There are many kinds of locks. Padlocks, mortise locks, deadbolt locks, window locks, combination locks and a variety of electronic systems which have evolved in modern times. But it is the basic lock and key that I have in mind here.
Keys come in a variety of sizes and shapes, but when it comes to opening a specific lock, one needs to have the correct key. That is, the key must be notched in all the right places in order to activate the inner workings of the lock, to unlock it when inserted and turned.
If you have ever made duplicate keys at a locksmiths, you've observed how the "blank" is matched to the original and, by grinding grooves and notches, the locksmith creates another key that will work the same lock.
In a sense, we are like blank keys which must be ground and polished to fit specific locks. As we submit to the grinding, we are being shaped for a purpose. Our sufferings are not meaningless. A little more filing here, a little bit there, and as the notches and grooves are cut into us, we find ourselves becoming most excellently formed to unlock the real treasures God has prepared for us.
I am becoming the key that will unlock the door to my own future successes as I trust the Master locksmith to complete the good work He has begun in me.