Every night when you get home after a hard working day, pour 10- 15 centimetres of cold, almost icy, water in the bathtub or in a bowl for your feet.
If you do not have water from the refrigerator, add a greater amount of ice to tap water and make it icy. Do not add hot water. Then put your feet in the bowl and tap in the water for 15 seconds.
Then wipe your feet with a rough terry towel and put on wool socks. Repeat this procedure every night without interruptions and will soon significantly strengthen your immunity.
If you already have had flu issues, that is a reason more to get started with this method of body strengthening. In that case, tap barefoot in icy water every 4 hours.
Do not worry that you will worsen your condition, on the contrary, such a tempering of the body will strengthen your immunity.