The Second Monday of October is health and sports day in Japan. This holiday was established in 1966 to commemorate the 1964 Olympics which were held in Tokyo. This holiday had been on October 10th until the year 2000 when it was moved to the second Monday of October. This time of year in Japan the weather is generally pretty good and the reason the Summer Olympics were held in October was in part to avoid tsuyu - the rainy season. That Olympics was the first one held in a non-western nation and introduced Volleyball and Judo to the Olympics.
This day is for recognizing sport's importance for a healthy body and mind. Many sporting events are held through out Japan on this day. Many schools and business's have Undoukai (a sport's festival). In undoukai, children are usually divided into two teams (red and white) and compete for their teams. Common events include tsunahiki (tug of war), tamaire game, kibasen (cavalry battle), creative dance, track and field events, and more.
Tamaire is a game in which you take about 200 stuffed balls, 2 baskets and 2 poles to hold the baskets (more if more players). The winner is determined by seeing how many balls can be thrown into each basket within a certain time. Traditionally there are two teams; one is the Red-team and the other is the White-team. Each team has about 100-stuffed balls colored Red or White. The balls are placed on the ground first and the children pick them up and throw them into the basket, which is on a pole about 1.5 meters or 2 meters high. There is even a league that plays this and championship tournaments. For the tournaments there are official rules and standardized equipment. The characters in the Azumanga Daioh anime can be seen playing this during their sports festival.
I like the idea of a day to promote health and exercise because too many people are living too sedentary lifestyles and eating fatty foods leading to obesity. While obesity is not a real large problem in Japan (10% of population obese up from 3% in 1970's), it is becoming a larger and larger problem in many countries (like USA, Mexico, and China). A holiday that promotes exercise is a good thing, that should be adopted in many countries. Even in Japan there are many people extremely concerned since children in particular are getting fatter and in the last 15 years the number of people with diabetes in Japan has increased 50%.