Getting colds and illnesses can put you in bed for several days, which could mean missing out on important occasions and events, having to skip a week of work and experiencing plenty of disruption in your life. Apart from that, you'll feel awful and will spend days wondering when you're going to feel better and what you can do to help yourself recover. Unfortunately, once you've caught an illness, getting rid of it is a lot harder than preventing it in the first place. Therefore, boosting your immune system is one of the best ways to help yourself stay healthy and fit.