Today's diary

I was supposed to go take a swimming class after my work today.
I decided to excercise very hard to [lose my weight from July] so I am cycling and swimming these days.
However, I didn't want to go swimming that much today, although I didn't have a lot to do in the office.
I don't know why.
I guess it's because of the weather. It's the rainy season and getting cloudy here in Korea.
I think it brings me down and I have no energy.
I want sunny days back as soon as possible.

General Notes:

--Swimming class is generic, so you would use "a" instead of "the." "The" would be applicable if you were talking about a specific swimming class: "...the swimming class at [named place]."

--While "like" and "want" are both statements of bias, they are used in different ways. "Like" would be used if you were only talking about swimming in general ("I don't like swimming."). "Want" would be used if you were talking about the action of doing it ("I didn't want to go swimming.").

--Because "rainy season" is specific, it would be "It's the rainy season..."

--Being "down" only references mood if phrased correctly. "Brings me down" is a common phrase to imply a depressed mood. You could also say "...it makes me feel down..." to better indicate 'mood'.

--Generally the opposite of 'rainy' is 'sunny'

I was supposed to take swimming class after my work today. 

I decided to exercise very hard to lose my weight from July so I am cycling and swimming these days.
However I didn't like to go swimming that much today although I didn't have a lot to do in the office.

I don't know why.

I guess it's because of the weather. It's the rainy season and getting cloudy here in Korea.

I think it makes me feel down and I have no energy. 

I want shiny days to come back as soon as possible.