English Standard Version (ESV)
If you measure your life by happiness, it'll plummet in challenging times, because you won't have any external signs that things are going well.
If you measure it by joy, however, that's something deeper that can sustain you in trials, because joy is something too deep to be disrupted by waves on the surface. Joy that results from a knowledge of the presence and grace of God can co-exist with suffering, because there is nothing contradictory. We can experience joy and happiness, and we can experience joy and sorrow, because that joy dwells at a level that cannot be taken from us, because nothing in the world or beyond the world can separate us from the love of God fully revealed in Jesus Christ.