"You're doing God's work." Even though the word "God" is used, it's not really religious; I hear it used by religious and non-religious people. The meaning is more like, "You're doing important work." It soothes the pain indirectly, by implying that the work is worthwhile and appreciated.
It can be used to encourage someone doing something frustrating or physically/emotionally draining, often something selfless (taking care of an elderly person) or far beyond the skills of the speaker (performing surgery). "Keep it up, you're doing God's work."
It can be used to express empathy and lighten the mood. You walk into a room where Alice is cleaning up her child's vomit. "Hey, Alice... oh... you're doing God's work."
It can also be used sarcastically, when you think someone is wasting their time. Bob is replying to racist trolls on reddit, trying to debate them with long, well-thought-out comments full of logic and reason. "Wow, Bob... you're doing God's work, man."