[header] How to pretend you are not sick [title] Keep an energetic voice intonation. [step] If you want everyone to think that you're not sick, it's important that your energy level appears normal. An easy way to trick people into thinking you're okay is to maintain a healthy level of energy. 
Try to say everything with enthusiasm, and stay away from mumbling. [substeps] Be aware of the tone and pitch of your voice.