Chinese are very conscious about their health, and wellness. Despite the ever growing fast-food industry, the idea of good health is very much alive. In the early mornings and late evenings, old persons can be seen doing some simple choreographed dances while some practice Taijichuan.
But for the younger generation, there is no time for this since some are busy working while some are studying. The foreigners are caught in-between, and it may be tough to choose whether to forget about exercise altogether or join the dances. However, the city has one of the largest stadiums in China. The Nanjing Olympics Sports Stadium. Here you can do a jog, play football on the lawns, street skating on the smooth paths, or altogether take a walk and enjoy the scenery.
I would greatly recommend street inline skating because of the small investment required and the large spaces for skating. First, a pair of high quality boots will cost 200 Yuan at Decathlon Sports Mega Store.
This is a large store for the expat community and they have all kinds of sports. Friendly staff who can speak English. Be sure to know exactly what you want to buy since one can easily be swayed by the vast items available. Also a helmet for 30 Yuan if you are not pro yet, but all the same safety is important.
To get to the Stadium take Metro Line 2 and alight at Nanjing Stadium East. This will be 2 Yuan at most. Line 1 also goes to the Stadium but on the West. Unless there are misc activities like Car Shows, Product Launches or the Nanjing 2014 Youth Olympics, the area is quiet with just few people taking a quick shortcut through the stadium. Its very clean and ambient.
Take out you boots, racket or whatever sport equipment you have and do some exercise. The arena remains closed unless prior arrangement. There are tennis, swimming and table-tennis mini-competitions always underway so one can dive in and maybe join a team. For those who fancy taking a walk and taking pictures, this is the time. In spring the stadium is full of color.
Get out and enjoy.