YOU SAID:
I went on a long walk today
INTO JAPANESE
今日は長い散歩に行きました
BACK INTO ENGLISH
Today I went for a long walk
INTO JAPANESE
今日は、長い散歩
BACK INTO ENGLISH
Today, the long walk
INTO JAPANESE
今日では、長い散歩
BACK INTO ENGLISH
Today, the long walk
That didn't even make that much sense in English.