Ziarat Ashura is a recommended act and thus one should recite it according to one's capacity, i.e. if 100 is difficult, then 10 is sufficient
An alternative is to spread the 100 curse and salaam throughout the day, i.e. recite the ziarat in the morning, and spread the 100 curse and salaam across your free time during the day and conclude the last sajdah and 2 rakaat prayer at night. This is something which the scholars have mentioned.
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