I don't think we should ever stop coloring just because we are adults! It can be just as relaxing for us as it is for children, slowing down to take deep breathes and giving yourself permission to create. These are mandalas which you can make yourself, buy, or print out online for free. Mandala means wholeness or circle in Sanskrit, and it's very pleasing for the eyes and the brain. Light a candle, put on some music, and get out your colored pencils!