Keep in mind, everyone’s tolerance level for colds and sniffles varies — one person feels like he can sustain a normal workout routine, while another feels too draggy to even consider it. But even if you fall into the latter category, you might still want to find the wherewithal to hit the gym — just be sure to clean the gym machines when you’re done with them. “Studies show that exercise is beneficial because it can boost your immune system before, during and after sickness,” says Nicola Finely, M.D., integrative medicine specialist at Canyon Ranch in Tucson.