In my case I studied engineering drawing at school so thought I would easily understand CAD, I have worked with computers all of my life, but school was so long ago that I really had to learn CAD from scratch.
I find it very gratifying to visualise something on the screen and then print it and have it in your hands a few hours later.
EDIT - just uploaded the first pool skimmer design, no photo of the real thing because its in the pool !!https://www.youmagine.com/designs/swiming-pool-skimmer