There are some fantastic ideas and advice shared here 
I’m raising my hand too- as not only a witch, but someone who works in a creative field- motivation definitely comes and goes. It can be quite a challenge at times!
Adding to everyone’s wise words and suggestions, I’ve found that working with Carnelian helps- as it is a stone of creativity and motivation 
There are some more resources and additional suggestions that can be found in the following threads:
Good luck and Blessed be! 