First of all, take your meds. Number one cause of not feeling well for me is being late on my meds.
Second of all, laugh. When your CVS pharmacist calls and asks if you have any (more) prescriptions for him to fill, just chuckle at the humor of the situation. How many people get to be on first-name basis with their pharmacist? How nice to be considered a regular at the corner drugstore, missed when absent too long. Similarly, when your 3-year-old daughter mentions in a voice quivering with emotion that she loves you even though you're bald, let it tickle your funny bone as opposed to striking a nerve. She meant it as the sincerest compliment, but you're allowed to laugh till you choke when she's out of earshot.
Finally, fake it till you make it. It applies to playing in the marching band in high school and again when up against a serious illness. If you don't feel well, pretend you do. Get dressed (not-withstanding the beauty of your paisley pajamas), do the things you would do on a normal day, and turn the corners of your mouth up.
And in all likelihood, you'll still feel grumpy and gross. But at least you got a laugh and got some stuff done.
P.S. I would like to clarify what I mean when I say "you're not feeling good." It is a distinctly different feeling than "feeling like death itself." If you are superwoman (or man),you should follow my instructions regardless of which feeling you have at that moment. If you are not endowed with powers beyond those of mere mortals, feeling like death itself definitely means "go back to bed and binge on Project Runway."