Prof. Dr. Sergey Bubnovsky a well-known Moscow specialist for kinesitherapy, recommends an easy method to boost immunity.
Every evening when you get home, after a hard day put 10-15cm completely cold water in a tub. Do not add warm water! Enter barefoot in a bathtub and tap with your feet in cold water only 10-15 seconds!
After that, exit the bathtub and rub your feet with terry cloth and put on wool socks. Do this every evening and so you will strengthen immunity.
Whether you already have a cold, that is more reason to strengthen your immunity. In that case, tap with bare feet in cold water every four hours. Without fear that you will endanger your condition, on the contrary this will strengthen your immunity, recommends Dr. Sergey.