How easy should singing feel?
You should have the ability to sing from the bottom to the extreme top of your vocal range, with a smooth, controlled, even feel to your voice. Also, you need to eliminate any “breaks” in your voice, where you “flip” or sing in different sounding voices in your lower and upper ranges. You should keep the same comfortable feel in your voice that you have when you speak, so you don’t try to “reach” for high notes, or try to push out high notes. As this balance is produced in your voice, you are able to sing with greater power throughout your entire range, without strain, and without wearing out your voice.