I had wondered the same things a while back. I recommend that you go to YouTube and look up Brad's Greenhouse channel, then search it for live sphagnum moss. He has a few good videos on taking care of it properly. I'm sure others here will have first-hand advice as well.
It's just really high humidity and strong light. You have to understand that mosses doesn't have roots and that they take in water by their "leafs". So a high humidity and high light would be enough.
Depending on where did you get it from. The zoomed ones are able to grow back. I've had couple strands growing out green leaves. However, you have to keep them under stable conditions and have a ton of patience for them to grow. They are really slow when they start to grow.
Keep it water-logged and always moist in bright lighting. It can withstand full sun so long as it always wet. Some people find success in raising it in tubs of shallow water. I find that if it is harvested very fresh, it will usually start growing within a few weeks or months. This temperate moss that you posted will do best in the long run if it is outdoors in an area that has true winters, but it will survive and grow for several seasons in a subtropical/tropical climate before it degrades.