I will add... it is hard... because you are training the body to do things it wasn't designed to do. These are exotic motor skills and coordinations that have to be trained. IN a sense, it is a "trick"... like gymnastics or ice skating. Unless you are a whale, bird, porpoise or cricket... we are not born singers. Singing has nothing to do with survival of the species. We don't need to sing, to survive as a species. That is why it is a learned and trained behavior.
Just because you have two arms and two hands, does that mean you know how to do a beautiful cartwheel across the floor? NO! Just because you have a voice ( a speaking system ), that doesn't mean it is prepared to SING.
You have to train and get to work developing these strengths, motor skills and more... including tuning your ear to hear exotic sound colors, find resonance, etc... there is a LOT to it that is not natural.