Yes, this does have to be every once in a while, Since I do two hour sets, and sometimes three hour sets 3 to 4 days a week Sometimes right off 20 minutes and I start feeling fatigue I usually use that fatigue to start singing in my lower register and put more resonance into my tone, think deep deep Bass But I can’t stay there every song so I have a little trick.. I opened up my mouth very wide, of course, I turned away from the audience And I pull my tongue out as far as I can and hold it out for a while. I do this about two or three times. It tends to loosen all of the tension around my chest neck, and where it counts And then resume with a song that’s a little easier in my upper register to get the mechanics going in the right direction But it comes with a little downfall once I do that I have to sing most of the rest of my songs in my upper register I have a very very large octave range.. When I say get it going, it tends to give me a little more focus and energy