Read the given sentences and choose the correct modal auxiliaries to fill in the blanks.
I ______ go for walk everyday when I was working in Philadelphia.

The correct answer is: Would

The modal auxiliary verb would has a variety of functions and uses. It is used in place of will for things that happened or began the past. When a sentence expresses a future possibility, expectation, intention or inevitability that began in the past. 'I would go for walk everyday when I was working in Philadelphia', here the word 'would' used to express past habit.