You should say:
What the activity is
When and where you usually do it
how you do it
and explain why it can keep you fit
I’m an outgoing person so that I like keeping myself busy even if I’m not
working. Riding my bicycle in my spare time is my favorite activity. Last year,
I moved to Xiamen. It is a city famous for cycling friendly. So I bought the
bike, and from then on I formed the habit of cycling. At first, I cycled to work
everyday, gradually, I started cycling for fun—going through some parks and down
by the riverside. Not until I joined the Cycling Club did I have the different
experience of cycling. It is a club gathering a group of people who have common
interests in cycling. They often get about on the weekends. So I joined in and
became a member of them. Sometime we planned a long journey. Normally, we just
go on a short trip about 20 miles to enjoy the day. Cycling does enrich my life.
Most importantly, it is an efficient way to keep fit. Now, there is no need for
me to do the exercise in the gym regularly. Cycling can help me shape the body.
Now, I am healthy physically and mentally.