As Ines said, not giving in to your brain key to this process. If you can allow yourself to calm down and listen to your brain, you might hear the negative messages it's giving you. You know, "Oh no, what if I'm getting sick, I hate being sick, what if it's the flu, what if I have to stay home sick, where did I get it, what if it's something else..." and so on. The more you give in to this negative self-talk, the more likely you are to stay stuck.
Once you really hear this self-defeating talk, you can counteract it. For example: "It's not likely to be the flu, I've been through this before, it's just TMS trying to distract me, and Hey, Brain, that is NOT necessary! I'm going to drink a bunch of water, and I'm going to get a good night's sleep, and whatever this is will be gone by morning!"
You can also take advantage of the placebo effect if that interests you. I do this all the time, because I believe (along with some researchers who are trying to figure out how to harness it) that using a placebo helps my positive conscious brain to visualize the outcome that I want. Like meditators sometimes use a visual or auditory mantra -it's just a tool for the brain to focus on. I'll take extra Vitamin C and echinacea if I feel like I'm coming down with something, along with lots of extra water which I visualize as flushing out the virus.
I know that both C and echinacea have been debunked as effective, but like I say - for me they are tools around which to marshal my immune system. Neuroscientists are piling up more evidence all the time that belief is a powerful agent for change.
Sometimes, if I'm feeling really stressed and foggy-headed, I'll take an acetaminophen (just one) which has been shown to calm emotional distress along with physical pain - again, it might be the placebo effect, but if the placebo effect works because our brains are able to create a physiological change, then I'm all for using it. It's just another tool in the toolkit.