I did yoga training with my friend today, and then we had fruit milk shakes and lunch today. My body felt limber and refreshed after training, and I felt my body temperature was higher than normal. I remembered a little while ago, I read an article about human’s body temperature. It suggests that human’s body temperatures are gradually dropped over history, because our physical activities, such as hunting and running, are steadily decreasing. Other factors include extensive usage of air conditioning. In the past, our body temperatures were much higher, usually over 37 degrees, than today. During the past three years of pandemic, I often got my body temperature checked in public places, and my body temperature had been below 36.5 degrees. I guess that might also be a self protective reaction of my body to the health screening scheme at that time, when we could get into trouble with a high body temperature. However, as our body temperatures have been declined, our immune system weakens, we are more easily to catch cold and affected by virus nowadays.