I can make my heart race at will. I can also decide to shit and/or piss on command, merely thinking about smoking DMT. Whenever i anticipate it, my body starts prepping itself, by purging everything that needs to go. I always feel the urge to shit or piss before and sometimes after DMT. Sometimes nothing comes out. But i still go, to convince my body "don't worry, we won't shit ourselves while in hyperspace."
The shivers are also there. Not from cold, more from nervous excitement.