My family has a joke about hard/horrible/terrible/frustrating things building character- like most jokes there is truth to it. This verse is telling us not to simply endure it but to find joy in it. This verse is hard for me to swallow. I do not find it natural to take pleasure from my pain.
But the promise is the verse is sweet- that trouble-those trials- are making me more like Christ. Refining my faith. Making me mature. Completing me. I still struggle to find joy in pain, but the promise of being like him is something to rejoice over!