An important way to build “kindness muscles” is to empathize with Others’ problems.
Imagine your friend is in a deep, dark hole. “Sympathy” means standing at the top of the hole, peering in, and saying “Oh, that’s so hard!” “Empathy” means crawling into the hole and being there with them.
Moses, went to the slave labor field and put his shoulder to the grindstone. He felt others’ pain as his own, and helped alleviate that burden.