My grandfather worked in a blacksmith shop when he was a boy, and he used to tell me, when I was a little boy myself, how he had toughened himself up so he could stand the rigors of blacksmithing.
One story was how he had developed his arm and shoulder muscles. He said he would stand outside behind the house and, with a 5-pound potato sack in each hand, extend his arms straight out to his sides and hold them there as long as he could.
After a while he tried 10-pound potato sacks, then 50-pound potato sacks and finally he got to where he could lift a 100-pound potato sack in each hand and hold his arms straight out for more than a full minute!
Next, he started putting potatoes in the sacks.
I suspect we're all like that at times. We understand (intellectually, at least) the value of trials. We understand that the testing of our faith produces patience (James 1:3). We understand that the fiery trials serve to purify our faith (I Peter 1:7). And we are quite content to hold the potato sacks -- as long as God doesn't put any potatoes in them!
It's much harder to see the benefit of trials when they are so overwhelming as to seem to be crushing. As Job said, "For the thing I greatly feared has come upon me, and what I dreaded has happened to me." (Job 3:25)
But empty potato sacks will never build muscles. And light trials will never develop the kind of qualities that God seeks to develop in our lives.
"My brethren, count it all joy when you fall into various trials, knowing that the testing of your faith produces patience. But let patience have its perfect work, that you may be perfect and complete, lacking nothing." (James 1:2-4)
May the trials you are going through today serve the strengthen the muscles of your spiritual life.