Yes, you are required, unless you qualify for one of the exemptions, which are few in number and are related to genuine hardship.
The right of Trial by Jury is articulated in Article III of the Constitution. In order to have a Jury you must have jurors, which is left up to the states. In Michigan, it's the Judicature Act of 1961, I believe.
http://www.legislature.mi.gov/(S(dhdk24j13ztmn155fuozls55))/mileg.aspx?page=MCLIndex&objectname=mcl-236-1961-13
The success of our legal system depends on intelligent people serving on juries as the finder of fact. When smart people don't participate it leads to bad outcomes.