I don't normally get upset in these posts but I have to disagree with the statement

"you can take voice lessons forever, and nothing you learn will equal the value of what I just stated above"

Voice lessons are an absolute if you intend to sing for extended periods. Correct breathing and posture, along with an appreciation of the capabilties of your voise, will allow you to do the job and not ruin your vocal chords in the process.

And dont be afraid to change the keys to suit your voice. We are not all Pavarotti's.