Coziness is hard to define, but you know it when you feel it. For me, it's the sensation that arises when everything is just so: the temperature is right, your body is comfortable, there's a pleasing atmosphere, and you're either doing something you enjoy or doing nothing at all. The classic images of coziness conjure a roaring fire in a wooden cabin somewhere remote and being gathered up in wool blankets, reading a novel. But coziness can also mean going on a walk on a warm Spring day with a dear friend, catching up about nothing.
Coziness is hard to force, but I also think we'd be happier on the whole if we paid more due to coziness in everyday life. If offices had big cushy armchairs and candlelight, I'd bet my bottom dollar that employees would be more excited to return to the workplace. But maybe we'd be too busy taking afternoon naps for anything to get done. But if you're not cozy right now, take a gander a these memes and they might help get you there.