Your lessons actually works for me. What's the trick to be able to sing for many hours and not get tired or loose power at the high notes
The best way to sing for many hours without getting tired, especially without loosing power on the high notes is to sing with proper technique. Here is an explanation and solution for EXACTLY what you are looking for. :) http://www.singbetterin3days.com/recordings/the-best-way-to-sing-higher-without-straining
If you aren't able to click on the link, just copy and paste it into your internet browser.