Like most things that have a glowing pigment in them you will have to get some light to it. Because of some issues with UV we wouldn’t recommend leaving these guys out on a windowsill for too long but if you have a high lumen light/torch this is a great way to get your glow on!
Simply hold your toy to/under the light for a couple of minutes and this should set it a-glowing, these will dim over time but just hit it with the touch again and it’s recoup it’s brightness!